Google's advertising programs are independent of our search results. Search results display on the left side of our results page; ads appear on the right and in the colored box at the top. Participation in an advertising program doesn't positively or negatively affect inclusion or ranking in the Google search results. Inclusion and ranking are free services; we don't accept payment to expedite inclusion or improve a site's ranking for particular keywords. Learn more about how Google ranks pages.

Google's spiders regularly crawl the web to rebuild our index. Crawls are based on many factors such as PageRank, links to a page, and crawling constraints such as the number of parameters in a URL. Any number of factors can affect the crawl frequency of individual sites.

Our crawl process is algorithmic; computer programs determine which sites to crawl, how often, and how many pages to fetch from each site. We don't accept payment to crawl a site more frequently. For tips on maintaining a crawler-friendly website, please visit our webmaster guidelines.

The site search box, which appears under the search results for some sites, lets you restrict your search to the selected site. For example, if the search box appears under the result for www.example.com, typing peanuts in the site search box will search the site www.example.com for the word "peanuts". It's the same as performing a site: search, like this: peanuts site:example.com.

The site search box makes it easier for users to refine their searches, and our experiments have found that this makes it faster to find the exact page they are looking for.

Webmasters don't have to optimize their sites to make the site search box appear. We don't display this box for all sites, but only when we determine - based on our user search data - that it would be useful to our users. As we refine this feature, the sites for which it appears may change.

You can also try other web search features supported by Google.