.NET Framework is a Microsoft software platform designed for developing web-based and Windows-based applications, offering a shift from client-centric to server-centric development. It features a Common Language Runtime (CLR) that supports multiple languages and provides automatic memory management, while ASP.NET allows the creation of web applications using various .NET languages. ADO.NET facilitates data access and XML support, and Visual Studio.NET serves as the integrated development environment for building applications.