Why Google is so good
There are literally billions of websites online. The same subject, keywords and content appear over and over. Which sites should appear first? Deciding the most appropriate results, quickly and accurately is the job of the search engine. Google does this job very well.
Search spiders
Google uses software to 'crawl' the web, jumping from link to link, reading the entire content of each page visited. These search 'spiders' visit time and time again to examine every aspect of a website including structure, content, code and links. Spider technology is not unusual, it is now used by all the leading search engines. However, the advanced ways in which Google is able to compare the data collected is what has put them on top.
Google PageRank
PageRank is the way in which Google measures the importance of one page compared to another.
When calculating PageRank, not only the site content, structure and links are considered, but importantly, Google also counts pages on other websites that link to you. Every link to your site is counted as a vote for your site. If the linking site has a high PageRank, the vote counts even more. A page passes 85% of it's PageRank to the pages it links to. This is evenly distributed between the links, although links higher up the page do benefit more.
Delivering results
To order the search results with the most important appearing first, Google combines PageRank with how relevant page content is to a search phrase.
This winning combination enables Google to deliver reliable, accurate results.
Related links
The perfect search engine
"Understands exactly what you mean and gives you back exactly what you want."Larry Page - Google co-founder
Interesting fact
Googles computation uses an amazing 500 million variables and 2 billion terms!