Microsoft Exchange functions in two ways:

• As an Advanced Business Class Mail Server. Exchange supports different mail protocols (RPC over HTTPS, MAPI, IMAP and POP) used either on Microsoft Outlook or a web browser
• As an Information Sharing Collaboration server. Much more powerful than simple email, Microsoft Exchange allows users to share information, either by using Microsoft Outlook on the desktop, using Outlook Web Access through a browser, or when mobile using a BlackBerry, PocketPC or SmartMobile device.

Exchange server turns Microsoft Outlook from a simple personal information management tool to a powerful tool that supports group collaboration. New features include public folders to which everyone can contribute and view files, calendars for scheduling meetings or reserving resources like conference rooms, common address books for sharing contact information, and much more. So why doesn't everyone who wants to share data with Outlook just install Exchange?

The answer is: cost and complexity.