SharePoint is a web-based, collaborative platform that integrates with Microsoft Office. SharePoint is primarily sold as a document management and storage system, but the product is highly configurable and usage varies substantially between organizations.
Sharepoint consists of several components. There are the Windows SharePoint Services (WSS), the Microsoft Office SharePoint Server (MOSS) and Microsoft Search Server. Each bring their own functionality to the table and build upon each other.
Windows SharePoint Services function the basic functionality that Gartner calls Basic Content Services. It offers the user access to Versioning and Check-in/Checkout functionality. WSS can then be extended through the use of the applets to add additional collaborative functions like email alerts, shared calendars, etc.
Microsoft Office SharePoint Server (MOSS) sits on top of WSS and adds additional features, both to the underlying WSS layer as well as additional ways for the end-user to interact with the repository. The data resides in a SQL Database. Using Webparts it can then present this information to the user using a wide range of different modules and for interaction in different business scenarios. These include such diverse applications as Collaboration, Document management, Records Management, Workflow, Personalization, more complex metadata models as well as Blogs and Wikis from the Web 2.0 side.
Finally there is the Microsoft Search Server, an Enterprise Search engine that provides advanced indexing and searching capabilities that can be integrated into a MOSS Web-based interface.
Microsoft itself describes SharePoint as Collaboration, Portal, Search, Enterprise Content Management (ECM) , Business process management (BPM) and Business intelligence (BI), so again a lot to choose from.