No, it’s not smartphones, overeating, or sugar.

Everyday practices affect brain health. Good brain practices increase memory and cognition.

Bad behaviors increase stress, which destroys brain cells.

Bad behaviors can reverse evolution and diminish the brain. So, avoid these practices for brain health.

1. The silent assassin

Introverts appreciated quarantine.

Before the pandemic, they needed excuses to remain home; thereafter, they had enough.

I am an introvert, and I didn’t hate quarantine. There are billions of people like me who avoid people.

Social relationships are important for brain health. Social anxiety harms your brain.

Antisocial behavior changes brains. It lowers IQ and increases drug abuse risk.

What you can do is as follows:

• Make a daily commitment to engage in conversation with a stranger. Who knows, you might turn out to be your lone mate.

• Get outside for at least 30 minutes each day.

• Shop for food locally rather than online.

• Make a call to a friend you haven't spoken to in a while.

2. Try not to rush things.

People love hustle culture. This economy requires a side gig to save money.

Long hours reduce brain health. A side gig is great until you burn out.

Work ages your wallet and intellect. Overworked brains age faster and lose cognitive function.

Working longer hours can help you make extra money, but it can harm your brain.

Side hustle but don't overwork.

What you can do is as follows:

• Decide what hour you are not permitted to work after.

• Three hours prior to night, turn off your laptop.

• Put down your phone and work.

• Assign due dates to each task.

3. Location is everything!

The environment may cause brain fog. High pollution can cause brain damage.

Air pollution raises Alzheimer's risk. Air pollution causes cognitive and behavioral abnormalities.

Polluted air can trigger early development of incurable brain illnesses, not simply lung harm.

Your city's air quality is uncontrollable. You may take steps to improve air quality.

In Delhi, schools and colleges are closed to protect pupils from polluted air. So I've adapted.

What you can do is as follows:

• To keep your mind healthy and young, make an investment in a high-quality air purifier.

• Enclose your windows during the day.

• Use a N95 mask every day.

4. Don't skip this meal.

Fasting intermittently is trendy. Delaying breakfast to finish fasting is frequent.

Some skip breakfast and have a hefty lunch instead.

Skipping breakfast might affect memory and focus. Skipping breakfast causes low cognition, delayed responsiveness, and irritation.

Breakfast affects mood and productivity.

Intermittent fasting doesn't prevent healthy breakfasts.

What you can do is as follows:

• Try to fast for 14 hours, then break it with a nutritious breakfast.

• So that you can have breakfast in the morning, eat dinner early.

• Make sure your breakfast is heavy in fiber and protein.

5. The quickest way to damage the health of your brain

Brain health requires water. 1% dehydration can reduce cognitive ability by 5%.

Cerebral fog and mental clarity might result from 2% brain dehydration. Dehydration shrinks brain cells.

Dehydration causes midday slumps and unproductivity. Water improves work performance.

Dehydration can harm your brain, so drink water throughout the day.

What you can do is as follows:

• Always keep a water bottle at your desk.

• Enjoy some tasty herbal teas.

• With a big glass of water, begin your day.

• Bring your own water bottle when you travel.

Conclusion

Bad habits can harm brain health. Low cognition reduces focus and productivity.

Unproductive work leads to procrastination, failure, and low self-esteem.

Avoid these harmful habits to optimize brain health and function.

Ready to quit full-time? No worries.

Baby Boomer retirement has accelerated since COVID-19 began. In 2020, 29 million boomers retire. Over 3 million more than in 2019. 75 million Baby Boomers will retire by 2030.

First, quit your work to enjoy retirement. Leave a professional legacy. Your retirement will start well. It all starts with a retirement letter.

Retirement Letter

Retirement letters are formal resignation letters. Different from other resignation letters, these don't tell your employer you're leaving. Instead, you're quitting.

Since you're not departing over grievances or for a better position or higher income, you may usually terminate the relationship amicably. Consulting opportunities are possible.

Thank your employer for their support and give them transition information.

Resignation letters aren't merely a formality. This method handles wages, insurance, and retirement benefits.

Retirement letters often accompany verbal notices to managers. Schedule a meeting before submitting your retirement letter to discuss your plans. The letter will be stored alongside your start date, salary, and benefits in your employee file.

Retirement is typically well-planned. Employers want 6-12 months' notice.

Summary

• Guidelines for Giving Retirement Notice

• Components of a Successful Retirement Letter

• Template for Retirement Letter

• Ideas for Samples of Retirement Letters

• First Example of Retirement Letter

• Second Example of Retirement Letter

• Third Example of Retirement Letter

• Fourth Example of Retirement Letter

• Fifth Example of Retirement Letter

• Sixth Example of Retirement Letter

• Seventh Example of Retirement Letter

• Eighth Example of Retirement Letter

• Ninth Example of Retirement Letter

• Tenth Example of Retirement Letter

• Frequently Asked Questions

• 1. What is a letter of retirement?

• 2. Why should you include a letter of retirement?

• 3. What information ought to be in your retirement letter?

• 4. Must I provide notice?

• 5. What is the ideal retirement age?

Guidelines for Giving Retirement Notice

While starting a new phase, you're also leaving a job you were qualified for. You have years of experience. So, it may not be easy to fill a retirement-related vacancy.

Talk to your boss in person before sending a letter. Notice is always appreciated. Properly announcing your retirement helps you and your organization transition.

How to announce retirement:

• Learn about the retirement perks and policies offered by the company. The first step in figuring out whether you're eligible for retirement benefits is to research your company's retirement policy.

• Don't depart without providing adequate notice. You should give the business plenty of time to replace you if you want to retire in a few months.

• Help the transition by offering aid. You could be a useful resource if your replacement needs training.

• Contact the appropriate parties. The original copy should go to your boss. Give a copy to HR because they will manage your 401(k), pension, and health insurance.

• Investigate the option of working as a consultant or part-time. If you desire, you can continue doing some limited work for the business.

• Be nice to others. Describe your achievements and appreciation. Additionally, express your gratitude for giving you the chance to work with such excellent coworkers.

• Make a plan for your future move. Simply updating your employer on your goals will help you maintain a good working relationship.

• Use a formal letter or email to formalize your plans. The initial step is to speak with your supervisor and HR in person, but you must also give written notice.

Components of a Successful Retirement Letter

To write a good retirement letter, keep in mind the following:

• A formal salutation. Here, the voice should be deliberate, succinct, and authoritative.

• Be specific about your intentions. The key idea of your retirement letter is resignation. Your decision to depart at this time should be reflected in your letter. Remember that your intention must be clear-cut.

• Your deadline. This information must be in resignation letters. Laws and corporate policies may both stipulate a minimum amount of notice.

• A kind voice. Your retirement letter shouldn't contain any resentments, insults, or other unpleasantness. Your letter should be a model of professionalism and grace. A straightforward thank you is a terrific approach to accomplish that.

• Your ultimate goal. Chaos may start to happen as soon as you turn in your resignation letter. Your position will need to be filled. Additionally, you will have to perform your obligations up until a successor is found. Your availability during the interim period should be stated in your resignation letter.

• Give us a way to reach you. Even if you aren't consulting, your company will probably get in touch with you at some point. They might send you tax documents and details on perks. By giving your contact information, you can make this process easier.

Template for Retirement Letter

Identify

Title you held

Address

Supervisor's name

Supervisor’s position

Company name

HQ address

Date

[SUPERVISOR],

1.

Inform that you're retiring. Include your last day worked.

2.

Employer thanks. Mention what you're thankful for. Describe your accomplishments and successes.

3.

Helping moves things ahead. Plan your retirement. Mention your consultancy interest.

Sincerely,

[Signature]

First and last name

Phone number

Personal Email

Ideas for Samples of Retirement Letters

First Example of Retirement Letter

Martin D. Carey

123 Fleming St

Bloomfield, New Jersey 07003

(555) 555-1234

June 6th, 2022

Willie E. Coyote

President

Acme Co

321 Anvil Ave

Fairfield, New Jersey 07004

Dear Mr. Coyote,

This letter notifies Acme Co. of my retirement on August 31, 2022.

There has been no other organization that has given me that sense of belonging and purpose.

My fifteen years at the helm of the Structural Design Division have given me‌ ‌a‌ ‌strong sense‌ ‌of‌ ‌purpose. I’ve been fortunate to have your support, and I’ll be always grateful for the opportunity you offered me.

I had a difficult time making this decision. ‌As a result of finding a small property in Arizona where we will be able to spend our remaining days together, my wife and I have decided to officially retire.

In spite of my regret at being unable to contribute to the firm we’ve built, I believe it is wise to move on.

My heart will always belong to Acme Co. ‌Thank you for the opportunity and best of luck in the years to come.

Sincerely,

Martin D. Carey

Second Example of Retirement Letter

Gustavo Fring

Los Pollas Hermanos

12000–12100 Coors Rd SW,

Albuquerque, New Mexico 87045

Dear Mr. Fring,

I write this letter to announce my formal retirement from Los Pollas Hermanos as manager, effective October 15.

As an employee at Los Pollas Hermanos, I appreciate all the great opportunities you have given me. ‌It has been a pleasure to work with and learn from my colleagues for the past 10 years, and I am looking forward to my next challenge.

If there is anything I can do to assist during this time, please let me know.

Sincerely,

Linda T. Crespo

Third Example of Retirement Letter

William M. Arviso

4387 Parkview Drive

Tustin, CA 92680

May 2, 2023

Tony Stark

Owner

Stark Industries

200 Industrial Avenue

Long Beach, CA 90803

Dear Tony:

I’m writing to inform you that my final day of work at Stark Industries will be May14, 2023. ‌When that time comes, I intend‌ ‌to‌ ‌retire.

As I embark on this new chapter in my life, I would like to thank you and the entire Stark Industries team for providing me with so many opportunities. ‌You have all been a pleasure to work with and I will miss you all when I retire.

I am glad to assist you with the transition in any way I can to ensure your new hire has a seamless experience. ‌All ongoing projects will be completed until my retirement date, and all key information will be handed over‌ ‌to‌ ‌the‌ ‌team.

Once again, thank you for the opportunity to be part of the Stark Industries team. ‌All the best to you and the team in the days to come.

Please do not hesitate to contact me if you require any additional information. ‌In order to finalize my retirement plans, I’ll meet with HR and can provide any details that may be necessary.

Sincerely,

(Signature)

William M. Arviso

Fourth Example of Retirement Letter

Garcia, Barbara

First Street, 5432

New York City, NY 10001

(1234) (555) 123–1234

1 October 2022

Gunther

Owner

Central Perk

199 Lafayette St.

New York City, NY 10001

Mr. Gunther,

The day has finally arrived. ‌As I never imagined, I will be formally retiring from Central Perk on November 1st, 2022.

Considering how satisfied I am with my current position, this may surprise you. ‌It would be best if I retired now since my health has deteriorated, so I think this is a good time to do so.

There is no doubt that the past‌ ‌two‌ ‌decades‌ ‌have‌ ‌been‌ ‌wonderful. ‌Over the years, I have seen a small coffee shop grow into one of the city’s top‌ ‌destinations.

It will be hard for me to leave this firm without wondering what more success we could have achieved. But I’m confident that you and the rest of the Central Perk team will achieve great things.

My family and I will never forget what you’ve done for us, and I am grateful for the chance you’ve given me. My house is always open to you.

Sincerely Yours

Garcia, Barbara

Fifth Example of Retirement Letter

Pat Williams

618 Spooky Place

Monstropolis, 23221

123–555–0031

pwilliams@email.com

Feb. 16, 2022

Mike Wazowski

Co-CEO

Monters, Inc.

324 Scare Road

Monstropolis

Dear Mr. Wazowski,

As a formal notice of my upcoming retirement, I am submitting this letter. ‌I will be leaving Monters, Inc. on‌ ‌April‌ ‌13.

These past 10 years as a marketing associate have provided me with many opportunities. ‌Since we started our company a decade ago, we have seen the face of harnessing screams change dramatically into harnessing laughter. ‌During my time working with this dynamic marketing team, I learned a lot about customer behavior and marketing strategies. ‌Working closely with some of our long-standing clients, such as Boo, was a particular pleasure.

I would be happy to‌ ‌assist‌ ‌with‌ ‌the‌ ‌transition‌ ‌following‌ ‌my‌ ‌retirement. ‌It would be my pleasure to assist in the hiring or training of‌ ‌my‌ ‌replacement. ‌In order to spend more time with my family, I will also be able to offer part-time consulting services.

After I retire, I plan to cash out the eight unused vacation days I’ve accumulated and take my pension as a lump sum.

Thank you for the opportunity to work with Monters, Inc. ‌In the years to come, I wish you all the best!

Sincerely,

Paul Williams

Sixth Example of Retirement Letter

Dear Micheal,

As In my tenure at Dunder Mifflin Paper Company, I have given everything I had. It has been an honor to work here. But‌ ‌I‌ ‌have‌ ‌decided‌ ‌to‌ ‌move on to new challenges and retire from my position — mainly bears, beets, and Battlestar Galactia.

I appreciate the opportunity to work here and learn so much. During my time at this company, I will always remember the good times and memories we shared. Wishing you all the best in the future.

Sincerely,

Dwight K. Shrute

Your signature

May 16

Seventh Example of Retirement Letter

Greetings, Bill

I am announcing my retirement from Initech, effective March 15, 2023.

Over the course of my career here, I’ve had the privilege of working with so many talented and inspiring people.

In 1999, when I began working as a customer service representative, we were a small organization located in a remote office park.

The fact that we now occupy a floor of the Main Street office building with over 150 employees continues to amaze me.

I am looking forward to spending more time with family and traveling the country in our RV. Although I will be sad to leave.

Please let me know if there are any extra steps I can take to facilitate this transfer.

Sincerely,

Frankin, RenitaEighth Example of Retirement Letter

Height Example of Retirement Letter

Bruce,

Please accept my resignation from Wayne Enterprises as Marketing Communications Director. My last day will be August 1, 2022.

The decision to retire has been made after much deliberation. Now that I have worked in the field for forty years, I believe it is a good time to begin completing my bucket list.

It was not easy for me to decide to leave the company. Having worked at Wayne Enterprises has been rewarding both professionally and personally. There are still a lot of memories associated with my first day as a college intern.

My intention was not to remain with such an innovative company, as you know. I was able to see the big picture with your help, however. Today, we are a force that is recognized both nationally and internationally.

In addition to your guidance, the bold, visionary leadership of our company contributed to the growth of our company.

My departure from the company coincides with a particularly hectic time. Despite my best efforts, I am unable to postpone my exit.

My position would be well served by an internal solution. I have a more than qualified marketing manager in Caroline Crown. It would be a pleasure to speak with you about this.

In case I can be of assistance during the switchover, please let me know. Contact us at (555)555–5555. As part of my responsibilities, I am responsible for making sure all work is completed to Wayne Enterprise’s stringent requirements. Having the opportunity to work with you has been a pleasure. I wish you continued success with your thriving business.

Sincerely,

Cash, Cole

Marketing/Communications

Ninth Example of Retirement Letter

Norman, Jamie

2366 Hanover Street

Whitestone, NY 11357

555–555–5555

jamie.norman@email.com

15 October 2022

Mr. Lippman

Head of Pendant Publishing

600 Madison Ave.

New York, New York

Respected Mr. Lippman,

Please accept my resignation effective‌ ‌November‌ ‌1,‌ ‌2022.

Over the course of my ten years at Pendant Publishing, I’ve had a great deal of fun and I’m quite grateful for all the assistance I’ve received.

It was a pleasure to wake up and go to work every day because of our outstanding corporate culture and the opportunities for promotion and professional advancement available to me.

While‌ ‌I am excited about retiring, I am going to miss being part of our team. ‌It’s my hope that I’ll be able to maintain the friendships I’ve formed here for a long time to come.

In case I can be of assistance prior to or following my departure, please let me know. ‌If I can assist in any way to ensure a smooth transfer to my successor, I would be delighted to do so.

Sincerely,

Signed (hard copy letter)

Norman, Jamie

Tenth Example of Retirement Letter

17 January 2023

Greg S. Jackson

Cyberdyne Systems

18144 El Camino Real,

Sunnyvale, CA

Respected Mrs. Duncan,

I‌ ‌am‌ ‌writing‌ ‌to‌ ‌inform you that I will be resigning from Cyberdyne Systems as of March 1, 2023. I’m grateful to have had this opportunity, and it was a difficult decision to make.

My development as a programmer and as a more seasoned member of the organization has been greatly assisted by your coaching.

I have been proud of Cyberdyne Systems’ ethics and success throughout my 25 years at the company. Starting as a mailroom clerk and currently serving as head programmer.

The portfolios of our clients have always been handled with the greatest care by my colleagues. It is our employees and services that have made Cyberdyne Systems the success it is today.

During my tenure as head of my division, I’ve increased our overall productivity by 800 percent, and I expect that trend to continue after‌ ‌I‌ ‌retire.

In light of the fact that the process of replacing me may take some time, I would like to offer my assistance in any way I can.

The greatest contender for this job is Troy Ledford, my current assistant.

Also, before I leave, I would be willing to teach any partners how to use the programmer I developed to track and manage the development of Skynet.

Over the next few months, I’ll be enjoying vacations with my wife as well as my granddaughter moving‌ ‌to‌ ‌college.

If Cyberdyne Systems has any openings for consultants, please let me know. ‌It has been a pleasure working with you over the last 25 years. I appreciate your concern and care.

Sincerely,

Greg S, Jackson

Questions and Answers

1. What is a letter of retirement?

Retirement letters tell your supervisor you're retiring. This informs your employer that you're departing, like a letter. A resignation letter also requests retirement benefits.

Supervisors frequently receive retirement letters and verbal resignations. Before submitting your retirement letter, meet to discuss your plans. This letter will be filed with your start date, salary, and benefits.

2. Why should you include a letter of retirement?

Your retirement letter should explain why you're leaving. When you quit, your manager and HR department usually know. Regardless, a retirement letter might help you leave on a positive tone. It ensures they have the necessary papers.

In your retirement letter, you tell the firm your plans so they can find your replacement. You may need to stay in touch with your company after sending your retirement letter until a successor is identified.

3. What information ought to be in your retirement letter?

Format it like an official letter. Include your retirement plans and retirement-specific statistics. Date may be most essential.

In some circumstances, benefits depend on when you resign and retire. A date on the letter helps HR or senior management verify when you gave notice and how long.

In addition to your usual salutation, address your letter to your manager or supervisor.

The letter's body should include your retirement date and transition arrangements. Tell them whether you plan to help with the transition or train a new employee. You may have a three-month time limit.

Tell your employer your job title, how long you've worked there, and your biggest successes. Personalize your letter by expressing gratitude for your career and outlining your retirement intentions. Finally, include your contact info.

4. Must I provide notice?

Two-week notice isn't required. Your company may require it. Some state laws contain exceptions.

Check your contract, company handbook, or HR to determine your retirement notice. Resigning may change the policy.

Regardless of your company's policy, notification is standard. Entry-level or junior jobs can be let go so the corporation can replace them.

Middle managers, high-level personnel, and specialists may take months to replace. Two weeks' notice is a courtesy. Start planning months ahead.

You can finish all jobs at that period. Prepare transition documents for coworkers and your replacement.

5. What is the ideal retirement age?

Depends on finances, state, and retirement plan. The average American retires at 62. The average retirement age is 66, according to Gallup's 2021 Economy and Personal Finance Survey.

Remember:

• Before the age of 59 1/2, withdrawals from pre-tax retirement accounts, such as 401(k)s and IRAs, are subject to a penalty.

• Benefits from Social Security can be accessed as early as age 62.

• Medicare isn't available to you till you're 65,

• Depending on the year of your birth, your Full Retirement Age (FRA) will be between 66 and 67 years old.

• If you haven't taken them already, your Social Security benefits increase by 8% annually between ages 6 and 77.

Don't promote it.

I rarely read a post on how Rich Dad, Poor Dad motivated someone to grow rich or change their investing/finance attitude. Rich Dad, Poor Dad is a sham, though. This book isn't worth anyone's attention.

Robert Kiyosaki, the author of this garbage, doesn't deserve recognition or attention. This first finance guru wanted to build his own wealth at your expense. These charlatans only care about themselves.

The reason why Rich Dad, Poor Dad is a huge steaming piece of trash

The book's ideas are superficial, apparent, and unsurprising to entrepreneurs and investors. The book's themes may seem profound to first-time readers.

Apparently, starting a business will make you rich.

The book supports founding or buying a business, making it self-sufficient, and being rich through it. Starting a business is time-consuming, tough, and expensive. Entrepreneurship isn't for everyone. Rarely do enterprises succeed.

Robert says we should think like his mentor, a rich parent. Robert never said who or if this guy existed. He was apparently his own father. Robert proposes investing someone else's money in several enterprises and properties. The book proposes investing in:

“have returns of 100 percent to infinity. Investments that for $5,000 are soon turned into $1 million or more.”

In rare cases, a business may provide 200x returns, but 65% of US businesses fail within 10 years. Australia's first-year business failure rate is 60%. A business that lasts 10 years doesn't mean its owner is rich. These statistics only include businesses that survive and pay their owners.

Employees are depressed and broke.

The novel portrays employees as broke and sad. The author degrades workers.

I've owned and worked for a business. I was broke and miserable as a business owner, working 80 hours a week for absolutely little salary. I work 50 hours a week and make over $200,000 a year. My work is hard, intriguing, and I'm surrounded by educated individuals. Self-employed or employee?

Don't listen to a charlatan's tax advice.

From a bad advise perspective, Robert's tax methods were funny. Robert suggests forming a corporation to write off holidays as board meetings or health club costs as business expenses. These actions can land you in serious tax trouble.

Robert dismisses college and traditional schooling. Rich individuals learn by doing or living, while educated people are agitated and destitute, says Robert.

Rich dad says:

“All too often business schools train employees to become sophisticated bean-counters. Heaven forbid a bean counter takes over a business. All they do is look at the numbers, fire people, and kill the business.”

And then says:

“Accounting is possibly the most confusing, boring subject in the world, but if you want to be rich long-term, it could be the most important subject.”

Get rich by avoiding paying your debts to others.

While this book has plenty of bad advice, I'll end with this: Robert advocates paying yourself first. This man's work with Trump isn't surprising.

Rich Dad's book says:

“So you see, after paying myself, the pressure to pay my taxes and the other creditors is so great that it forces me to seek other forms of income. The pressure to pay becomes my motivation. I’ve worked extra jobs, started other companies, traded in the stock market, anything just to make sure those guys don’t start yelling at me […] If I had paid myself last, I would have felt no pressure, but I’d be broke.“

Paying yourself first shouldn't mean ignoring debt, damaging your credit score and reputation, or paying unneeded fees and interest. Good business owners pay employees, creditors, and other costs first. You can pay yourself after everyone else.

If you follow Robert Kiyosaki's financial and business advice, you might as well follow Donald Trump's, the most notoriously ineffective businessman and swindle artist.

This book's popularity is unfortunate. Robert utilized the book's fame to promote paid seminars. At these seminars, he sold more expensive seminars to the gullible. This strategy was utilized by several conmen and Trump University.

It's reasonable that many believed him. It sounded appealing because he was pushing to get rich by thinking like a rich person. Anyway. At a time when most persons addressing wealth development advised early sacrifices (such as eschewing luxury or buying expensive properties), Robert told people to act affluent now and utilize other people's money to construct their fantasy lifestyle. It's exciting and fast.

I often voice my skepticism and scorn for internet gurus now that social media and platforms like Medium make it easier to promote them. Robert Kiyosaki was a guru. Many people still preach his stuff because he was so good at pushing it.

ERC165 (or EIP-165) is a standard utilized by various open-source smart contracts like Open Zeppelin or Aavegotchi.

What's it? You must implement? Why do we need it? I'll describe the standard and answer any queries.

What is ERC165

ERC165 detects and publishes smart contract interfaces. Meaning? It standardizes how interfaces are recognized, how to detect if they implement ERC165, and how a contract publishes the interfaces it implements. How does it work?

Why use ERC165? Sometimes it's useful to know which interfaces a contract implements, and which version.

Identifying interfaces

An interface function's selector. This verifies an ABI function. XORing all function selectors defines an interface in this standard. The following code demonstrates.

// SPDX-License-Identifier: UNLICENCED
pragma solidity >=0.8.0 <0.9.0;

interface Solidity101 {
    function hello() external pure;
    function world(int) external pure;
}

contract Selector {
    function calculateSelector() public pure returns (bytes4) {
        Solidity101 i;
        return i.hello.selector ^ i.world.selector;
        // Returns 0xc6be8b58
    }

    function getHelloSelector() public pure returns (bytes4) {
        Solidity101 i;
        return i.hello.selector;
        // Returns 0x19ff1d21
    }

    function getWorldSelector() public pure returns (bytes4) {
        Solidity101 i;
        return i.world.selector;
        // Returns 0xdf419679
    }
}

This code isn't necessary to understand function selectors and how an interface's selector can be determined from the functions it implements.

Run that sample in Remix to see how interface function modifications affect contract function output.

Contracts publish their implemented interfaces.

We can identify interfaces. Now we must disclose the interfaces we're implementing. First, import IERC165 like so.

pragma solidity ^0.4.20;

interface ERC165 {
    /// @notice Query if a contract implements an interface
    /// @param interfaceID The interface identifier, as specified in ERC-165
    /// @dev Interface identification is specified in ERC-165. 
    /// @return `true` if the contract implements `interfaceID` and
    ///  `interfaceID` is not 0xffffffff, `false` otherwise
    function supportsInterface(bytes4 interfaceID) external view returns (bool);
}

We still need to build this interface in our smart contract. ERC721 from OpenZeppelin is a good example.

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/introspection/ERC165.sol";
// ...

contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
  // ...

  function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
    return
      interfaceId == type(IERC721).interfaceId ||
      interfaceId == type(IERC721Metadata).interfaceId ||
      super.supportsInterface(interfaceId);
  }
  
  // ...
}

I deleted unnecessary code. The smart contract imports ERC165, IERC721 and IERC721Metadata. The is keyword at smart contract declaration implements all three.

Kind (interface).

Note that type(interface).interfaceId returns the same as the interface selector.

We override supportsInterface in the smart contract to return a boolean that checks if interfaceId is the same as one of the implemented contracts.

Super.supportsInterface() calls ERC165 code. Checks if interfaceId is IERC165.

function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
    return interfaceId == type(IERC165).interfaceId;
}

So, if we run supportsInterface with an interfaceId, our contract function returns true if it's implemented and false otherwise. True for IERC721, IERC721Metadata, andIERC165.

Conclusion

I hope this post has helped you understand and use ERC165 and why it's employed.

Have a great day, thanks for reading!

I recently wrote about getting VCs excited about Marketplace start-ups. SaaS founders became envious!

Understanding how people wire tens of millions is the only Series A hack I recommend.

Few people understand the intellectual process behind investing.

VC is risk management.

Series A-focused VCs must cover two risks.

1. Market risk

You need a large market to cross a threshold beyond which you can build defensibilities. Series A VCs underwrite market risk.

They must see you have reached product-market fit (PMF) in a large total addressable market (TAM).

2. Execution risk

When evaluating your growth engine's blitzscaling ability, execution risk arises.

When investors remove operational uncertainty, they profit.

Series A VCs like businesses with derisked revenue streams. Don't raise unless you have a predictable model, pipeline, and growth.

Please beat these 3 metrics before Series A:

Achieve $1.5m ARR in 12-24 months (Market risk)

Above 100% Net Dollar Retention. (Market danger)

Lead Velocity Rate supporting $10m ARR in 2–4 years (Execution risk)

Hit the 3 and you'll raise $10M in 4 months. Discussing 2/3 may take 6–7 months.

If none, don't bother raising and focus on becoming a capital-efficient business (Topics for other posts).

Let's examine these 3 metrics for the brave ones.

1. Lead Velocity Rate supporting €$10m ARR in 2 to 4 years

Last because it's the least discussed. LVR is the most reliable data when evaluating a growth engine, in my opinion.

SaaS allows you to see the future.

Monthly Sales and Sales Pipelines, two predictive KPIs, have poor data quality. Both are lagging indicators, and minor changes can cause huge modeling differences.

Analysts and Associates will trash your forecasts if they're based only on Monthly Sales and Sales Pipeline.

LVR, defined as month-over-month growth in qualified leads, is rock-solid. There's no lag. You can See The Future if you use Qualified Leads and a consistent formula and process to qualify them.

With this metric in your hand, scaling your company turns into an execution play on which VCs are able to perform calculations risk.

2. Above-100% Net Dollar Retention.

Net Dollar Retention is a better-known SaaS health metric than LVR.

Net Dollar Retention measures a SaaS company's ability to retain and upsell customers. Ask what $1 of net new customer spend will be worth in years n+1, n+2, etc.

Depending on the business model, SaaS businesses can increase their share of customers' wallets by increasing users, selling them more products in SaaS-enabled marketplaces, other add-ons, and renewing them at higher price tiers.

If a SaaS company's annualized Net Dollar Retention is less than 75%, there's a problem with the business.

Slack's ARR chart (below) shows how powerful Net Retention is. Layer chart shows how existing customer revenue grows. Slack's S1 shows 171% Net Dollar Retention for 2017–2019.

Slack S-1

3. $1.5m ARR in the last 12-24 months.

According to Point 9, $0.5m-4m in ARR is needed to raise a $5–12m Series A round.

Target at least what you raised in Pre-Seed/Seed. If you've raised $1.5m since launch, don't raise before $1.5m ARR.

Capital efficiency has returned since Covid19. After raising $2m since inception, it's harder to raise $1m in ARR.

P9's 2016-2021 SaaS Funding Napkin

In summary, less than 1% of companies VCs meet get funded. These metrics can help you win.

If there’s demand for it, I’ll do one on direct-to-consumer.

Cheers!