Google algorithm
The Google algorithm decides where your pages show up in the search results. The exact algorithm Google uses to rank your site is its best-kept secret. It is very extensive and weighs more than 200 factors. In 2013 Google gave its algorithm the name Hummingbird.
The basis of the Google algorithm
Google's core algorithm is built on PageRank. PageRank is calculated per page from the number of links (backlinks) pointing to it. Each link passes part of its PageRank to the page it links to, so a link from a page with a high PageRank is worth more than a link from a page with a low one. With smart internal linking you can build up a high internal PageRank.
The PageRank of a page is no longer public, but that does not mean Google stopped using it. Quite the opposite: PageRank is still an important part of the Google algorithm.
Additions to the Google algorithm
Google experiments with its algorithm all the time and changes it several times a day. Those are small adjustments and tweaks. A few times a year Google makes a major change, big enough to affect a large number of sites. Examples of major Google algorithm updates:
- Google Panda (targets low-quality pages)
- Google Penguin (targets low-quality links)
- Google Pirate (targets copyright infringers)
- Mobilegeddon (targets websites that are not mobile-friendly)
- RankBrain (Google's artificial intelligence that rewrites search queries)