Google Apps is a service from Google providing independently customizable versions of several Google products under a custom domain name. It features several Web applications with similar functionality to traditional office suites, including: Gmail, Google Groups, Google Calendar, Talk, Docs and Sites.
The Standard Edition is free and offers the same amount of storage as regular Gmail accounts. The Premier Edition, which offers additional e-mail storage, is available for an annual fee. The Education Edition, which is free, combines features from the Standard and Premier editions.