C# (pronounced "C-sharp") is a versatile, modern programming language developed by Microsoft. It's primarily used for developing a wide range of applications, from web to mobile to desktop apps. C# is part of the .NET framework, which provides a huge library of pre-written code to help with tasks from database connections to network communications. It’s known for its simplicity, efficiency, and strong typing, which makes it easier to catch errors early. Picture it as a powerful tool in a developer's arsenal, capable of building robust and high-performance software solutions.