Google is a corporation which offers various internet, online and mobility related services like Internet search, cloud computing and advertising technologies. Google also leads the development of the Android mobile operating system.
For questions that are about a specific Google service or application, please use a specific tag, such as (but not limited to): gmail, google-reader, etc. You can use this link to see a list of specific
google-* tags, or even better visit the tags page and type "google" into the search box to list them all.