The .NET Framework is a software development platform created by Microsoft that provides a consistent programming model for building and running applications on Windows. It includes the Common Language Runtime (CLR), which manages code execution, memory, and security, and the Base Class Library (BCL), offering pre-built classes for tasks like file handling, networking, and database access. Developers can use multiple languages such as C#, VB.NET, and F# to build desktop applications, web apps, and enterprise solutions. With its reliability, scalability, and strong integration with Windows, the .NET Framework has been a cornerstone of modern software development for decades.