How search engines work

Search engines are like libraries for the digital age.Instead of storing copies of books, they store copies of web pages.
When you type a query into a search engine, it looks through all the pages in its index and tries to return the most relevant results.To do this, it uses a computer program called an algorithm.
Nobody knows exactly how these algorithms work, but we do have clues, at least from Google.Here’s what they say on their “How search works” page:

• To give you the most useful information, Search algorithms look at many factors, including the words of your query, relevance and usability of pages, expertise of sources and your location and settings. The weight applied to each factor varies depending on the nature of your query – for example, the freshness of the content plays a bigger role in answering queries about current news topics than it does about dictionary definitions.

Speaking of Google, this is the search engine most of us use—at least for web searches. That’s because it has the most reliable algorithm by far.That said, there are tons of other search engines you can optimize for.

How SEO works

You might think of a search engine as a website you visit to type (or speak) a question into a box and Google, Yahoo!, Bing, or whatever search engine you're using magically replies with a long list of links to webpages that could potentially answer your question.

That's true. But have you ever stopped to consider what's behind those magical lists of links?

Here's how it works: Google (or any search engine you're using) has a crawler that goes out and gathers information about all the content they can find on the Internet. The crawlers bring all those 1s and 0s back to the search engine to build an index. That index is then fed through an algorithm that tries to match all that data with your query.