Google Apps is a Web-based and collaborative Software as a Service (SaaS) solution that customizes the proprietary Google platform and brand for businesses of all sizes, including large enterprises. Google Apps facilitates the provisioning of Google applications and user/enterprise management tools, including Gmail, Google Talk, Google Calendar, Google Docs, Google Videos and Google Cloud Connect.
Techopedia explains Google Apps
Google Apps is backed by the same infrastructure and resources provided by the standard Google services. It features 99.9 percent uptime availability, administrative support, and other corporate support features explicitly described in the Google Apps Service Level Agreement (SLA).
Google Apps customizes applications for different industries, as described below:
Google Apps (free): Gmail (up to ten free email accounts), Google Calendar, Google Sites, and Google Docs
Google Apps for education: Free applications for schools
Google Apps for business: Paid version, which provides Web-based application tools for collaboration
Google Apps for government: Web-based and government certified collaboration tools
Google Apps for nonprofit: Collaboration and communication tools for U.S. nonprofit organizations