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How Does Google Rank Pages

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How does Google decide rank web pages?

Crawling and Indexing

Spiders crawl the web ....

Google sends out Googlebot, a "spider," which crawls around the web following links to find web pages. The web pages are then indexed which basically inverts the data. The end result is an index of words with references to each web page containing each given word.

So when you type a word into google and ask for a search google then goes straight to it’s index of pages containing that word.

If you type 2 words into google, google then goes to it’s index for each word, then compares the indexes to find the pages that contain both words.

The next step is to rank the web pages in order of relevance.

Ranking Results

Google uses many factors in ranking.

High quality links ....

keywords .... positioning

One of these is PageRank which evaluates two things: how many links there are to a web page from other pages, and the quality of the linking sites. With PageRank, high-quality links from other good websites would be valued much more highly than links from less reputable or established sites.

Another consideration is how close together the words you are searching for. For example, if a document contains the words "civil" and "war" right next to each other, it might be more relevant than a document discussing the Revolutionary War that happens to use the word "civil" somewhere else on the page.

Also, if a page includes the words "civil war" in its title, that's a hint that it might be more relevant than a document with the title "19th Century American Clothing."
In the same way, if the words "civil war" appear several times throughout the page, that page is more likely to be about the civil war than if the words only appear once.

As a rule, Google tries to find pages that are both reputable and relevant. If two pages appear to have roughly the same amount of information matching a given query, we'll usually try to pick the page that more trusted websites have chosen to link to. Still, we'll often elevate a page with fewer links or lower PageRank if other signals suggest that the page is more relevant. For example, a web page dedicated entirely to the civil war is often more useful than an article that mentions the civil war in passing, even if the article is part of a reputable site such as Time.com.

Once we've made a list of documents and their scores, we take the documents with the highest scores as the best matches. Google does a little bit of extra work to try to show snippets – a few sentences – from each document that highlight the words that a user typed. Then we return the ranked URLs and the snippets to the user as results pages.

Matt Cutts

Matt Cutts is a software engineer in the quality group at Google. He spends his days trying to help good sites rank where they should and developing techniques that keep deceptive or spammy sites from showing up in Google's search. He also has a web log at http://www.mattcutts.com/blog/ that often discusses webmaster issues.