Ways Google determines the ranking of sites is through Crawling, Indexing, and Serving results.
- Crawling is the process in which Googlebot discovers new and updated pages. As Googlebot crawls through each site it detects links and adds them to the list of pages to crawl.
- Indexing is the compiling of all the pages Googlebot crawled into a massive index of all the words it sees and their location on each page. Also processes key content tags and and attributes, such as Title tags and ALT attributes.
- Serving Results searching the index and provides a result determined to be most relevant to the user. Relevancy is determined by over 200 things, one is PageRank. PageRank is the measure of importance of a page based on the incoming links from other pages.Each link to a page on your site from another site adds to your PageRank.