Webmaster Tools is a no-charge web service by Google for webmasters. It allows webmasters to check indexing status and optimize visibility of their websites. It has tools that let the webmasters:
- Submit and check a sitemap.
- Check and set the crawl rate, and view statistics about how Googlebot accesses a particular site.
- Generate and check a robots.txt file.
- List internal and external pages that link to the site.
- See what keyword searches on Google led to the site being listed in the SERPs, and the click through rates of such listings.
- View statistics about how Google indexes the site, and if it found any errors while doing it.
- Set a preferred domain (e.g. prefer wikipedia.org over www.wikipedia.org or vice versa), which determines how the site url is displayed in SERPs.