The Business Productivity Online Suite is a set of Microsoft hosted messaging and collaboration solutions including
Microsoft Exchange Online
Microsoft SharePoint Online
Microsoft Office Live Meeting
Microsoft Office Communications Online
These online services are designed to give your business streamlined communication with high availability, comprehensive security, and simplified IT management. When your company subscribes to one or more of the services, it connects to the rich interactivity of on-premises client and server applications with the flexibility and scalability of Web-based services.
Microsoft hosts the services, it reduces your company’s need to maintain IT services on site. Many organizations today are moving to this "software-plus-services" model, because it decreases the need to manage hardware and software.