Do you know that when you are searching on Google, you're not actually searching the web? Instead you're searching Google's index of the web.
Google, the search engine since 1998, has the largest database of indexed website, which is 2 times more than Yahoo! and Bing.
The Google index is the list of all the pages that Google has crawled and cached. And when we perform a search, Google pulls out pages and other information from this data.
Take a look at below infographic, created by Quicksprout, to learn more about how the world's largest search engine crawls and indexes web pages, as well as 7 most common reasons Google can't crawl your site and how to help Google crawl more pages.