The library is delivered together with Windows operating system. It contains many APIs and functions for working with security, the system register and other aspects of the Windows operating system. An Application Programming Interface is an abstract collection of functions, procedures or classes that support requests made by software applications. An API can be by accessed by applications written in either a specific or non-specific language, depending on whether its language dependent. An API typically provides an interface between a high level language, such as C++, and lower level machine code. This allows programs to develop complex applications without having knowledge of how to implement these features at the most basic level.