Do you know how Google’s crawler, Googlebot, handles conflicting directives in your robots.txt file? Do you know how to prevent a PDF file from being indexed? Do you know Googlebot’s favorite song? The answers to these questions (except for the last one ), along with lots of other information about controlling the crawling and indexing of your site, are now available on code.google.com:

Controlling crawling and indexing

Now site owners have a comprehensive resource where they can learn about robots.txt files, robots meta tags, and X-Robots-Tag HTTP header directives. Please share your comments, and if you have questions you can post them in our Webmaster Help Forum.