.NET is a Microsoft-supported framework designed for developing user-friendly web and desktop applications with features that enhance productivity, security, and performance. It includes key components like the Common Language Runtime (CLR), Framework Class Library (FCL), and Common Type System (CTS), which facilitate cross-language integration and efficient code execution. As an open-source framework, .NET supports multiple operating systems and offers a strong community for ongoing improvements, making it a preferred choice for businesses of all sizes.