More on Productivity

Recep İnanç
3 years ago
Effective Technical Book Reading Techniques
Technical books aren't like novels. We need a new approach to technical texts. I've spent years looking for a decent reading method. I tried numerous ways before finding one that worked. This post explains how I read technical books efficiently.
What Do I Mean When I Say Effective?
Effectiveness depends on the book. Effective implies I know where to find answers after reading a reference book. Effective implies I learned the book's knowledge after reading it.
I use reference books as tools in my toolkit. I won't carry all my tools; I'll merely need them. Non-reference books teach me techniques. I never have to make an effort to use them since I always have them.
Reference books I like:
Design Patterns: Elements of Reusable Object-Oriented Software
Refactoring: Improving the Design of Existing Code
You can also check My Top Takeaways from Refactoring here.
Non-reference books I like:
The Approach
Technical books might be overwhelming to read in one sitting. Especially when you have no idea what is coming next as you read. When you don't know how deep the rabbit hole goes, you feel lost as you read. This is my years-long method for overcoming this difficulty.
Whether you follow the step-by-step guide or not, remember these:
Understand the terminology. Make sure you get the meaning of any terms you come across more than once. The likelihood that a term will be significant increases as you encounter it more frequently.
Know when to stop. I've always believed that in order to truly comprehend something, I must delve as deeply as possible into it. That, however, is not usually very effective. There are moments when you have to draw the line and start putting theory into practice (if applicable).
Look over your notes. When reading technical books or documents, taking notes is a crucial habit to develop. Additionally, you must regularly examine your notes if you want to get the most out of them. This will assist you in internalizing the lessons you acquired from the book. And you'll see that the urge to review reduces with time.
Let's talk about how I read a technical book step by step.
0. Read the Foreword/Preface
These sections are crucial in technical books. They answer Who should read it, What each chapter discusses, and sometimes How to Read? This is helpful before reading the book. Who could know the ideal way to read the book better than the author, right?
1. Scanning
I scan the chapter. Fast scanning is needed.
I review the headings.
I scan the pictures quickly.
I assess the chapter's length to determine whether I might divide it into more manageable sections.
2. Skimming
Skimming is faster than reading but slower than scanning.
I focus more on the captions and subtitles for the photographs.
I read each paragraph's opening and closing sentences.
I examined the code samples.
I attempt to grasp each section's basic points without getting bogged down in the specifics.
Throughout the entire reading period, I make an effort to make mental notes of what may require additional attention and what may not. Because I don't want to spend time taking physical notes, kindly notice that I am using the term "mental" here. It is much simpler to recall. You may think that this is more significant than typing or writing “Pay attention to X.”
I move on quickly. This is something I considered crucial because, when trying to skim, it is simple to start reading the entire thing.
3. Complete reading
Previous steps pay off.
I finished reading the chapter.
I concentrate on the passages that I mentally underlined when skimming.
I put the book away and make my own notes. It is typically more difficult than it seems for me. But it's important to speak in your own words. You must choose the right words to adequately summarize what you have read. How do those words make you feel? Additionally, you must be able to summarize your notes while you are taking them. Sometimes as I'm writing my notes, I realize I have no words to convey what I'm thinking or, even worse, I start to doubt what I'm writing down. This is a good indication that I haven't internalized that idea thoroughly enough.
I jot my inquiries down. Normally, I read on while compiling my questions in the hopes that I will learn the answers as I read. I'll explore those issues more if I wasn't able to find the answers to my inquiries while reading the book.
Bonus!
Best part: If you take lovely notes like I do, you can publish them as a blog post with a few tweaks.
Conclusion
This is my learning journey. I wanted to show you. This post may help someone with a similar learning style. You can alter the principles above for any technical material.

Maria Stepanova
3 years ago
How Elon Musk Picks Things Up Quicker Than Anyone Else
Adopt Elon Musk's learning strategy to succeed.
Medium writers rank first and second when you Google “Elon Musk's learning approach”.
My article idea seems unoriginal. Lol
Musk is brilliant.
No doubt here.
His name connotes success and intelligence.
He knows rocket science, engineering, AI, and solar power.
Musk is a Unicorn, but his skills aren't special.
How does he manage it?
Elon Musk has two learning rules that anyone may use.
You can apply these rules and become anyone you want.
You can become a rocket scientist or a surgeon. If you want, of course.
The learning process is key.
Make sure you are creating a Tree of Knowledge according to Rule #1.
Musk told Reddit how he learns:
“It is important to view knowledge as sort of a semantic tree — make sure you understand the fundamental principles, i.e. the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang onto.”
Musk understands the essential ideas and mental models of each of his business sectors.
He starts with the tree's trunk, making sure he learns the basics before going on to branches and leaves.
We often act otherwise. We memorize small details without understanding how they relate to the whole. Our minds are stuffed with useless data.
Cramming isn't learning.
Start with the basics to learn faster. Before diving into minutiae, grasp the big picture.
Rule #2: You can't connect what you can't remember.
Elon Musk transformed industries this way. As his expertise grew, he connected branches and leaves from different trees.
Musk read two books a day as a child. He didn't specialize like most people. He gained from his multidisciplinary education. It helped him stand out and develop billion-dollar firms.
He gained skills in several domains and began connecting them. World-class performances resulted.
Most of us never learn the basics and only collect knowledge. We never really comprehend information, thus it's hard to apply it.
Learn the basics initially to maximize your chances of success. Then start learning.
Learn across fields and connect them.
This method enabled Elon Musk to enter and revolutionize a century-old industry.

Darshak Rana
3 years ago
17 Google Secrets 99 Percent of People Don't Know
What can't Google do?
Seriously, nothing! Google rocks.
Google is a major player in online tools and services. We use it for everything, from research to entertainment.
Did I say entertain yourself?
Yes, with so many features and options, it can be difficult to fully utilize Google.
#1. Drive Google Mad
You can make Google's homepage dance if you want to be silly.
Just type “Google Gravity” into Google.com. Then select I'm lucky.
See the page unstick before your eyes!
#2 Play With Google Image
Google isn't just for work.
Then have fun with it!
You can play games right in your search results. When you need a break, google “Solitaire” or “Tic Tac Toe”.
#3. Do a Barrel Roll
Need a little more excitement in your life? Want to see Google dance?
Type “Do a barrel roll” into the Google search bar.
Then relax and watch your screen do a 360.
#4 No Internet? No issue!
This is a fun trick to use when you have no internet.
If your browser shows a “No Internet” page, simply press Space.
Boom!
We have dinosaurs! Now use arrow keys to save your pixelated T-Rex from extinction.
#5 Google Can Help
Play this Google coin flip game to see if you're lucky.
Enter “Flip a coin” into the search engine.
You'll see a coin flipping animation. If you get heads or tails, click it.
#6. Think with Google
My favorite Google find so far is the “Think with Google” website.
Think with Google is a website that offers marketing insights, research, and case studies.
I highly recommend it to entrepreneurs, small business owners, and anyone interested in online marketing.
#7. Google Can Read Images!
This is a cool Google trick that few know about.
You can search for images by keyword or upload your own by clicking the camera icon on Google Images.
Google will then show you all of its similar images.
Caution: You should be fine with your uploaded images being public.
#8. Modify the Google Logo!
Clicking on the “I'm Feeling Lucky” button on Google.com takes you to a random Google Doodle.
Each year, Google creates a Doodle to commemorate holidays, anniversaries, and other occasions.
#9. What is my IP?
Simply type “What is my IP” into Google to find out.
Your IP address will appear on the results page.
#10. Send a Self-Destructing Email With Gmail,
Create a new message in Gmail. Find an icon that resembles a lock and a clock near the SEND button. That's where the Confidential Mode is.
By clicking it, you can set an expiration date for your email. Expiring emails are automatically deleted from both your and the recipient's inbox.
#11. Blink, Google Blink!
This is a unique Google trick.
Type “blink HTML” into Google. The words “blink HTML” will appear and then disappear.
The text is displayed for a split second before being deleted.
To make this work, Google reads the HTML code and executes the “blink” command.
#12. The Answer To Everything
This is for all Douglas Adams fans.
The answer to life, the universe, and everything is 42, according to Google.
An allusion to Douglas Adams' Hitchhiker's Guide to the Galaxy, in which Ford Prefect seeks to understand life, the universe, and everything.
#13. Google in 1998
It's a blast!
Type “Google in 1998” into Google. "I'm feeling lucky"
You'll be taken to an old-school Google homepage.
It's a nostalgic trip for long-time Google users.
#14. Scholarships and Internships
Google can help you find college funding!
Type “scholarships” or “internships” into Google.
The number of results will surprise you.
#15. OK, Google. Dice!
To roll a die, simply type “Roll a die” into Google.
On the results page is a virtual dice that you can click to roll.
#16. Google has secret codes!
Hit the nine squares on the right side of your Google homepage to go to My Account. Then Personal Info.
You can add your favorite language to the “General preferences for the web” tab.
#17. Google Terminal
You can feel like a true hacker.
Just type “Google Terminal” into Google.com. "I'm feeling lucky"
Voila~!
You'll be taken to an old-school computer terminal-style page.
You can then type commands to see what happens.
Have you tried any of these activities? Tell me in the comments.
Read full article here
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Benjamin Lin
3 years ago
I sold my side project for $20,000: 6 lessons I learned
How I monetized and sold an abandoned side project for $20,000
The Origin Story
I've always wanted to be an entrepreneur but never succeeded. I often had business ideas, made a landing page, and told my buddies. Never got customers.
In April 2021, I decided to try again with a new strategy. I noticed that I had trouble acquiring an initial set of customers, so I wanted to start by acquiring a product that had a small user base that I could grow.
I found a SaaS marketplace called MicroAcquire.com where you could buy and sell SaaS products. I liked Shareit.video, an online Loom-like screen recorder.
Shareit.video didn't generate revenue, but 50 people visited daily to record screencasts.
Purchasing a Failed Side Project
I eventually bought Shareit.video for $12,000 from its owner.
$12,000 was probably too much for a website without revenue or registered users.
I thought time was most important. I could have recreated the website, but it would take months. $12,000 would give me an organized code base and a working product with a few users to monetize.
I considered buying a screen recording website and trying to grow it versus buying a new car or investing in crypto with the $12K.
Buying the website would make me a real entrepreneur, which I wanted more than anything.
Putting down so much money would force me to commit to the project and prevent me from quitting too soon.
A Year of Development
I rebranded the website to be called RecordJoy and worked on it with my cousin for about a year. Within a year, we made $5000 and had 3000 users.
We spent $3500 on ads, hosting, and software to run the business.
AppSumo promoted our $120 Life Time Deal in exchange for 30% of the revenue.
We put RecordJoy on maintenance mode after 6 months because we couldn't find a scalable user acquisition channel.
We improved SEO and redesigned our landing page, but nothing worked.
Despite not being able to grow RecordJoy any further, I had already learned so much from working on the project so I was fine with putting it on maintenance mode. RecordJoy still made $500 a month, which was great lunch money.
Getting Taken Over
One of our customers emailed me asking for some feature requests and I replied that we weren’t going to add any more features in the near future. They asked if we'd sell.
We got on a call with the customer and I asked if he would be interested in buying RecordJoy for 15k. The customer wanted around $8k but would consider it.
Since we were negotiating with one buyer, we put RecordJoy on MicroAcquire to see if there were other offers.
We quickly received 10+ offers. We got 18.5k. There was also about $1000 in AppSumo that we could not withdraw, so we agreed to transfer that over for $600 since about 40% of our sales on AppSumo usually end up being refunded.
Lessons Learned
First, create an acquisition channel
We couldn't discover a scalable acquisition route for RecordJoy. If I had to start another project, I'd develop a robust acquisition channel first. It might be LinkedIn, Medium, or YouTube.
Purchase Power of the Buyer Affects Acquisition Price
Some of the buyers we spoke to were individuals looking to buy side projects, as well as companies looking to launch a new product category. Individual buyers had less budgets than organizations.
Customers of AppSumo vary.
AppSumo customers value lifetime deals and low prices, which may not be a good way to build a business with recurring revenue. Designed for AppSumo users, your product may not connect with other users.
Try to increase acquisition trust
Acquisition often fails. The buyer can go cold feet, cease communicating, or run away with your stuff. Trusting the buyer ensures a smooth asset exchange. First acquisition meeting was unpleasant and price negotiation was tight. In later meetings, we spent the first few minutes trying to get to know the buyer’s motivations and background before jumping into the negotiation, which helped build trust.
Operating expenses can reduce your earnings.
Monitor operating costs. We were really happy when we withdrew the $5000 we made from AppSumo and Stripe until we realized that we had spent $3500 in operating fees. Spend money on software and consultants to help you understand what to build.
Don't overspend on advertising
We invested $1500 on Google Ads but made little money. For a side project, it’s better to focus on organic traffic from SEO rather than paid ads unless you know your ads are going to have a positive ROI.

Marco Manoppo
2 years ago
Failures of DCG and Genesis
Don't sleep with your own sister.
70% of lottery winners go broke within five years. You've heard the last one. People who got rich quickly without setbacks and hard work often lose it all. My father said, "Easy money is easily lost," and a wealthy friend who owns a family office said, "The first generation makes it, the second generation spends it, and the third generation blows it."
This is evident. Corrupt politicians in developing countries live lavishly, buying their third wives' fifth Hermès bag and celebrating New Year's at The Brando Resort. A successful businessperson from humble beginnings is more conservative with money. More so if they're atom-based, not bit-based. They value money.
Crypto can "feel" easy. I have nothing against capital market investing. The global financial system is shady, but that's another topic. The problem started when those who took advantage of easy money started affecting other businesses. VCs did minimal due diligence on FTX because they needed deal flow and returns for their LPs. Lenders did minimum diligence and underwrote ludicrous loans to 3AC because they needed revenue.
Alameda (hence FTX) and 3AC made "easy money" Genesis and DCG aren't. Their businesses are more conventional, but they underestimated how "easy money" can hurt them.
Genesis has been the victim of easy money hubris and insolvency, losing $1 billion+ to 3AC and $200M to FTX. We discuss the implications for the broader crypto market.
Here are the quick takeaways:
Genesis is one of the largest and most notable crypto lenders and prime brokerage firms.
DCG and Genesis have done related party transactions, which can be done right but is a bad practice.
Genesis owes DCG $1.5 billion+.
If DCG unwinds Grayscale's GBTC, $9-10 billion in BTC will hit the market.
DCG will survive Genesis.
What happened?
Let's recap the FTX shenanigan from two weeks ago. Shenanigans! Delphi's tweet sums up the craziness. Genesis has $175M in FTX.
Cred's timeline: I hate bad crisis management. Yes, admitting their balance sheet hole right away might've sparked more panic, and there's no easy way to convey your trouble, but no one ever learns.
By November 23, rumors circulated online that the problem could affect Genesis' parent company, DCG. To address this, Barry Silbert, Founder, and CEO of DCG released a statement to shareholders.
A few things are confirmed thanks to this statement.
DCG owes $1.5 billion+ to Genesis.
$500M is due in 6 months, and the rest is due in 2032 (yes, that’s not a typo).
Unless Barry raises new cash, his last-ditch efforts to repay the money will likely push the crypto market lower.
Half a year of GBTC fees is approximately $100M.
They can pay $500M with GBTC.
With profits, sell another port.
Genesis has hired a restructuring adviser, indicating it is in trouble.
Rehypothecation
Every crypto problem in the past year seems to be rehypothecation between related parties, excessive leverage, hubris, and the removal of the money printer. The Bankless guys provided a chart showing 2021 crypto yield.
In June 2022, @DataFinnovation published a great investigation about 3AC and DCG. Here's a summary.
3AC borrowed BTC from Genesis and pledged it to create Grayscale's GBTC shares.
3AC uses GBTC to borrow more money from Genesis.
This lets 3AC leverage their capital.
3AC's strategy made sense because GBTC had a premium, creating "free money."
GBTC's discount and LUNA's implosion caused problems.
3AC lost its loan money in LUNA.
Margin called on 3ACs' GBTC collateral.
DCG bought GBTC to avoid a systemic collapse and a larger discount.
Genesis lost too much money because 3AC can't pay back its loan. DCG "saved" Genesis, but the FTX collapse hurt Genesis further, forcing DCG and Genesis to seek external funding.
bruh…
Learning Experience
Co-borrowing. Unnecessary rehypothecation. Extra space. Governance disaster. Greed, hubris. Crypto has repeatedly shown it can recreate traditional financial system disasters quickly. Working in crypto is one of the best ways to learn crazy financial tricks people will do for a quick buck much faster than if you dabble in traditional finance.
Moving Forward
I think the crypto industry needs to consider its future. This is especially true for professionals. I'm not trying to scare you. In 2018 and 2020, I had doubts. No doubts now. Detailing the crypto industry's potential outcomes helped me gain certainty and confidence in its future. This includes VCs' benefits and talking points during the bull market, as well as what would happen if government regulations became hostile, etc. Even if that happens, I'm certain. This is permanent. I may write a post about that soon.
Sincerely,
M.
James Brockbank
3 years ago
Canonical URLs for Beginners
Canonicalization and canonical URLs are essential for SEO, and improper implementation can negatively impact your site's performance.
Canonical tags were introduced in 2009 to help webmasters with duplicate or similar content on multiple URLs.
To use canonical tags properly, you must understand their purpose, operation, and implementation.
Canonical URLs and Tags
Canonical tags tell search engines that a certain URL is a page's master copy. They specify a page's canonical URL. Webmasters can avoid duplicate content by linking to the "canonical" or "preferred" version of a page.
How are canonical tags and URLs different? Can these be specified differently?
Tags
Canonical tags are found in an HTML page's head></head> section.
<link rel="canonical" href="https://www.website.com/page/" />These can be self-referencing or reference another page's URL to consolidate signals.
Canonical tags and URLs are often used interchangeably, which is incorrect.
The rel="canonical" tag is the most common way to set canonical URLs, but it's not the only way.
Canonical URLs
What's a canonical link? Canonical link is the'master' URL for duplicate pages.
In Google's own words:
A canonical URL is the page Google thinks is most representative of duplicate pages on your site.
— Google Search Console Help
You can indicate your preferred canonical URL. For various reasons, Google may choose a different page than you.
When set correctly, the canonical URL is usually your specified URL.
Canonical URLs determine which page will be shown in search results (unless a duplicate is explicitly better for a user, like a mobile version).
Canonical URLs can be on different domains.
Other ways to specify canonical URLs
Canonical tags are the most common way to specify a canonical URL.
You can also set canonicals by:
Setting the HTTP header rel=canonical.
All pages listed in a sitemap are suggested as canonicals, but Google decides which pages are duplicates.
Redirects 301.
Google recommends these methods, but they aren't all appropriate for every situation, as we'll see below. Each has its own recommended uses.
Setting canonical URLs isn't required; if you don't, Google will use other signals to determine the best page version.
To control how your site appears in search engines and to avoid duplicate content issues, you should use canonicalization effectively.
Why Duplicate Content Exists
Before we discuss why you should use canonical URLs and how to specify them in popular CMSs, we must first explain why duplicate content exists. Nobody intentionally duplicates website content.
Content management systems create multiple URLs when you launch a page, have indexable versions of your site, or use dynamic URLs.
Assume the following URLs display the same content to a user:
A search engine sees eight duplicate pages, not one.
URLs #1 and #2: the CMS saves product URLs with and without the category name.
#3, #4, and #5 result from the site being accessible via HTTP, HTTPS, www, and non-www.
#6 is a subdomain mobile-friendly URL.
URL #7 lacks URL #2's trailing slash.
URL #8 uses a capital "A" instead of a lowercase one.
Duplicate content may also exist in URLs like:
https://www.website.com
https://www.website.com/index.php
Duplicate content is easy to create.
Canonical URLs help search engines identify different page variations as a single URL on many sites.
SEO Canonical URLs
Canonical URLs help you manage duplicate content that could affect site performance.
Canonical URLs are a technical SEO focus area for many reasons.
Specify URL for search results
When you set a canonical URL, you tell Google which page version to display.
Which would you click?
https://www.domain.com/page-1/
https://www.domain.com/index.php?id=2
First, probably.
Canonicals tell search engines which URL to rank.
Consolidate link signals on similar pages
When you have duplicate or nearly identical pages on your site, the URLs may get external links.
Canonical URLs consolidate multiple pages' link signals into a single URL.
This helps your site rank because signals from multiple URLs are consolidated into one.
Syndication management
Content is often syndicated to reach new audiences.
Canonical URLs consolidate ranking signals to prevent duplicate pages from ranking and ensure the original content ranks.
Avoid Googlebot duplicate page crawling
Canonical URLs ensure that Googlebot crawls your new pages rather than duplicated versions of the same one across mobile and desktop versions, for example.
Crawl budgets aren't an issue for most sites unless they have 100,000+ pages.
How to Correctly Implement the rel=canonical Tag
Using the header tag rel="canonical" is the most common way to specify canonical URLs.
Adding tags and HTML code may seem daunting if you're not a developer, but most CMS platforms allow canonicals out-of-the-box.
These URLs each have one product.
How to Correctly Implement a rel="canonical" HTTP Header
A rel="canonical" HTTP header can replace canonical tags.
This is how to implement a canonical URL for PDFs or non-HTML documents.
You can specify a canonical URL in your site's.htaccess file using the code below.
<Files "file-to-canonicalize.pdf"> Header add Link "< http://www.website.com/canonical-page/>; rel=\"canonical\"" </Files>301 redirects for canonical URLs
Google says 301 redirects can specify canonical URLs.
Only the canonical URL will exist if you use 301 redirects. This will redirect duplicates.
This is the best way to fix duplicate content across:
HTTPS and HTTP
Non-WWW and WWW
Trailing-Slash and Non-Trailing Slash URLs
On a single page, you should use canonical tags unless you can confidently delete and redirect the page.
Sitemaps' canonical URLs
Google assumes sitemap URLs are canonical, so don't include non-canonical URLs.
This does not guarantee canonical URLs, but is a best practice for sitemaps.
Best-practice Canonical Tag
Once you understand a few simple best practices for canonical tags, spotting and cleaning up duplicate content becomes much easier.
Always include:
One canonical URL per page
If you specify multiple canonical URLs per page, they will likely be ignored.
Correct Domain Protocol
If your site uses HTTPS, use this as the canonical URL. It's easy to reference the wrong protocol, so check for it to catch it early.
Trailing slash or non-trailing slash URLs
Be sure to include trailing slashes in your canonical URL if your site uses them.
Specify URLs other than WWW
Search engines see non-WWW and WWW URLs as duplicate pages, so use the correct one.
Absolute URLs
To ensure proper interpretation, canonical tags should use absolute URLs.
So use:
<link rel="canonical" href="https://www.website.com/page-a/" />And not:
<link rel="canonical" href="/page-a/" />If not canonicalizing, use self-referential canonical URLs.
When a page isn't canonicalizing to another URL, use self-referencing canonical URLs.
Canonical tags refer to themselves here.
Common Canonical Tags Mistakes
Here are some common canonical tag mistakes.
301 Canonicalization
Set the canonical URL as the redirect target, not a redirected URL.
Incorrect Domain Canonicalization
If your site uses HTTPS, don't set canonical URLs to HTTP.
Irrelevant Canonicalization
Canonicalize URLs to duplicate or near-identical content only.
SEOs sometimes try to pass link signals via canonical tags from unrelated content to increase rank. This isn't how canonicalization should be used and should be avoided.
Multiple Canonical URLs
Only use one canonical tag or URL per page; otherwise, they may all be ignored.
When overriding defaults in some CMSs, you may accidentally include two canonical tags in your page's <head>.
Pagination vs. Canonicalization
Incorrect pagination can cause duplicate content. Canonicalizing URLs to the first page isn't always the best solution.
Canonicalize to a 'view all' page.
How to Audit Canonical Tags (and Fix Issues)
Audit your site's canonical tags to find canonicalization issues.
SEMrush Site Audit can help. You'll find canonical tag checks in your website's site audit report.
Let's examine these issues and their solutions.
No Canonical Tag on AMP
Site Audit will flag AMP pages without canonical tags.
Canonicalization between AMP and non-AMP pages is important.
Add a rel="canonical" tag to each AMP page's head>.
No HTTPS redirect or canonical from HTTP homepage
Duplicate content issues will be flagged in the Site Audit if your site is accessible via HTTPS and HTTP.
You can fix this by 301 redirecting or adding a canonical tag to HTTP pages that references HTTPS.
Broken canonical links
Broken canonical links won't be considered canonical URLs.
This error could mean your canonical links point to non-existent pages, complicating crawling and indexing.
Update broken canonical links to the correct URLs.
Multiple canonical URLs
This error occurs when a page has multiple canonical URLs.
Remove duplicate tags and leave one.
Canonicalization is a key SEO concept, and using it incorrectly can hurt your site's performance.
Once you understand how it works, what it does, and how to find and fix issues, you can use it effectively to remove duplicate content from your site.
