Microsoft Visual C++ (often abbreviated as MSVC or VC++) is a commercial (free version available), integrated development environment (IDE) product from Microsoft for the C, C++, and C++/CLI programming languages. It features tools for developing and debugging C++ code, especially code written for the Microsoft Windows API, the DirectX API, and the Microsoft .NET Framework.

Many applications require redistributable Visual C++ packages to function correctly. These packages are often installed independently of applications, allowing multiple applications to make use of the package while only having to install it once. These Visual C++ redistributable and runtime packages are mostly installed for standard libraries that many applications use.

Site: http://msdn.microsoft.com/en-us/vstudio/hh386302.aspx