Search Engine Basics

Learn How Search Engines Works?

A search engine is a program that finds, stores, and ranks web pages so it can answer your questions in a few seconds. When you type something into Google, you’re not searching the live web. You’re searching a saved copy of it that Google built ahead of time, then sorted to put the most useful pages first.
That whole process happens in three stages: crawling, indexing, and ranking. Get comfortable with those three words and the rest of search engine basics starts to make sense fast.

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What Is a Search Engine?

A search engine is software that helps you find information across the web without knowing the exact address of the page you need. Type a question or a phrase into the search box, called a query, and the search engine returns a list of pages it believes answer it, ranked from most to least useful.
People often mix up a search engine with a browser, but they’re not the same thing. A browser, like Chrome or Safari, is the window you use to view web pages. A search engine, like Google or Bing, is one of the services you can visit inside that window. You could open a browser and never touch a search engine at all, if you typed in website addresses directly.
Google handles the large majority of searches worldwide, but it’s far from the only search engine. Bing, Yahoo, DuckDuckGo, Yandex, Baidu, and Naver all run their own versions of the same basic system, each with its own approach to privacy, ranking, or regional focus.

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How Search Engines Work: Crawling, Indexing, Ranking

Think of a search engine like a library, how search engines work. Before a librarian can hand you a book, someone has to find it, catalogue it, and shelve it in order. Search engines do the same job across the entire web, billions of times over.

Crawling

Crawling is how a search engine discovers pages exist. Google uses an automated program called Googlebot, often just called a bot or a spider, that moves from link to link across the web, much like you’d click from one page to another. When Googlebot lands on a page, it reads the content and follows the links on that page to find more pages.
Site owners can guide this process with a file called robots.txt, which tells bots which parts of a site they’re allowed to visit, and an XML sitemap, which lists out the pages a site wants discovered. Google also limits how much of a site it crawls in a given period, a limit known as crawl budget, which matters more for very large sites than small ones.

Learn about crawling

Indexing

Finding a page isn’t the same as storing it. Once Googlebot crawls a page, Google decides whether to add it to the search index, which is the massive database it draws results from. A page can be crawled and still left out of the index if it’s thin content, a near duplicate of another page, or marked with a noindex tag telling Google not to store it.
Google’s own Search Central documentation describes crawling and indexing as two separate stages, and mixing them up is one of the most common points of confusion for people new to search engine basics. A page being indexed means it’s eligible to appear in results. It says nothing yet about where it might rank.

Learn about indexing

Ranking

Ranking is the stage that decides order. When you run a search, Google’s systems scan the index for pages relevant to your query, then sort them using a large set of signals: page experience, content relevance, expertise and trustworthiness, and many others Google has confirmed without publishing a full list. No outside source, including this one, has ever seen Google’s complete ranking system. Anyone claiming a finished list of ranking factors is guessing. What’s known comes from Google’s own statements, patent filings, and years of observed pattern in how results shift after named updates, such as Google’s Core Updates and the Helpful Content Update.
Learn about ranking

Explore the Basics

Topic
Types of Search Engines
What you'll learn
Crawler based, directory based, metasearch, and how they differ.
Topic
Keywords and Search Intent
What you'll learn

How the words you type shape what a search engine indexing actually is shows you.

Topic
SERP Features
What you'll learn
Featured snippets, People Also Ask, AI Overviews, and what each one means.
Topic
History of Search Engines
What you'll learn
From Archie and AltaVista to PageRank and beyond.
Topic
2026 AI Search
What you'll learn
How AI Overviews and chat based search are changing results.

Search Engine Basics Guides

Search by the Numbers

Google holds roughly 89 to 90 percent of global search market share as of 2026, according to StatCounter, though that figure shifts month to month and varies sharply by country. A growing share of searches now end without a click to any website at all, a pattern often called zero click search, as answer boxes and AI Overviews satisfy more questions directly on the results page. AI Overviews now appear on a meaningful portion of Google searches, particularly informational ones, though exact figures change as Google continues rolling the feature out. These numbers are a snapshot of where things stand right now, not a fixed fact, so treat any specific percentage you read anywhere, including here, as time stamped.
90%

Google’s share of global search traffic.

58%

Searches that end without a click to any website (zero-click searches).

47%

Google search results pages that show an AI Overview.

8.5B+
Searches processed by Google every day.

Frequently Asked Questions

A search engine is a tool that finds web pages matching what you type in, then sorts them by how useful they’re likely to be, so the best answers show up first.
Dozens exist worldwide, though a handful dominate. Google, Bing, Yahoo, DuckDuckGo, Yandex, and Baidu cover most of the traffic, with Naver leading in South Korea and Ecosia known for its environmental focus.
No. Google handles the most searches globally, but Bing powers Microsoft’s products and a portion of Yahoo’s results, DuckDuckGo focuses on privacy, and Yandex and Baidu lead in Russia and China.
Not at all. SEO, short for search engine optimization, is something website owners do to help their pages get found. As a searcher, you just type your question and read the results.

Start Learning Search Engine Basics

If this is new territory, start with How Search Engines Work, then move to Crawling, Indexing, and Ranking in that order. Each guide builds on the last, so by the end you’ll understand not just what shows up on a results page, but why.
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