Google search process is divided into three process:

1) Crawling and Indexing
Google use software known as “web crawlers” to discover publicly available webpages. The most well-known crawler is called “Googlebot.” Crawlers look at webpages and follow links on those pages, much like you would if you were browsing content on the web. They go from link to link and bring data about those webpages back to Google’s servers.

2) Algorithms
You want the answer, not trillions of webpages. Algorithms are computer programs that look for clues to give you back exactly what you want.
For a typical query, there are thousands, if not millions, of webpages with helpful information. Algorithms are the computer processes and formulas that take your questions and turn them into answers. Today Google’s algorithms rely on more than 200 unique signals or “clues” that make it possible to guess what you might really be looking for. These signals include things like the terms on websites, the freshness of content, your region and PageRank.

3) Fighting Spam
Every day, millions of useless spam pages are created. We fight spam through a combination of computer algorithms and manual review.
Spam sites attempt to game their way to the top of search results through techniques like repeating keywords over and over, buying links that pass PageRank or putting invisible text on the screen. This is bad for search because relevant websites get buried, and it’s bad for legitimate website owners because their sites become harder to find. The good news is that Google’s algorithms can detect the vast majority of spam and demote it automatically. For the rest, we have teams who manually review sites.