Google returns the right
results first.
Google uses a complicated mathematical analysis, calculated on more
than a billion hyperlinks on the web, to return high-quality search
results so you don't have to sift through junk. This analysis allows
Google to estimate the quality, or importance, of every web page it
returns. The importance of a web page is entirely independent of any
query. A page like www.google.com has high importance if
- Other pages with high importance point to
www.google.com
- Lots of other pages with high importance point to
www.google.com
This definition seems circular, and it is. Nonetheless, it yields a
well-defined notion of importance that makes finding high quality
sites easy.
Of course, important pages mean nothing to you if they don't match
your query, so Google uses sophisticated text-matching techniques to
find pages that are both important and relevant to your search. For
instance, when considering a page, Google looks at what the pages
linking to that page have to say about it.