DirectX 9.0c is a software development kit created by Microsoft that enhances multimedia and gaming experiences on Windows operating systems. Released in 2004, it provides a set of application programming interfaces (APIs) that allow developers to create high-performance graphics and sound in their applications. This version of DirectX introduced several improvements, including better support for 3D graphics and advanced shader capabilities. It also included features like Direct3D, which helps render 3D graphics more efficiently, making it popular among game developers and users seeking enhanced visual experiences in their software.