Google Webmaster Tools provides the following very useful services for your website:
Submit/check the sitemap for your website.
Adjust the crawl rate of the Google bots for your website and view the statistics.
Generate/check the robots.txt file for your website.
List the internal and external pages that link to your website.
Check what keyword searches led the site to being displayed in the Google search engine results pages and click-through rates for them.
Check statistics about how Google has indexed your website and whether it has found any issues while doing so.
Set a preferred domain name (e.g. yourdomain.com over
www.yourdomain.com or vice versa) which will determine how the site URL will be displayed in search engine results pages.