When you do a search on Google, you get your search results almost instantly. So how does Google trawl through the billions of pages on the web to deliver such quick results?
To rank your web pages in their search engine results pages (SERPs), Google has to do 3 things:
- Crawl your web pages
- Index your web pages in its database
- Decide how relevant your web pages are
Crawling your pages
Google sends out a computer program called a spider to index new and updated pages on the web. The spider (called Googlebot) is controlled by other computer programs. These programs decide which pages to crawl and how often.
The spiders start by crawling pages they have visited before. They also detect links they find on these pages and add them to the list of pages to crawl.
Indexing your pages
The spider processes information on each page it crawls, and stores it in Google’s index – a massive database of all the websites and web pages Google has crawled.
Google indexes all the words it sees on your site and where the words are. It doesn’t just index the ‘visible’ words you see on the page – it takes note of things like title tags, meta-description, file names, and the words used in links (anchor text) and much much more.
So, when you do a search on Google, most of the hard work is done. Google just dips into its databases, finds all relevant pages and then ranks them by what pages they think are most relevant to your search query.
Google uses over 200 ranking factors to decide how to rank your web pages. Anything from the country where your website is hosted, to the words used around links to your website, can affect your ranking.