SharePoint is a set of products and technologies that allows users to create, organize, share, and access information. It includes two main platforms - Windows SharePoint Services (WSS) which enables team collaboration, and Microsoft Office SharePoint Server (MOSS) which builds on WSS with additional features like enterprise search and content management. SharePoint uses a three-tier architecture with the presentation layer in ASP.NET, logic in .NET assemblies, and data stored in a SQL Server database. It is configured at the farm, web application, site, and web levels.