In computing, an abstraction layer or abstraction level is a way of hiding the implementation details of a particular set of functionality, allowing the separation of concerns to facilitate interoperability and platform independence. Software models that use layers of abstraction include the OSI 7-layer model for computer network protocols, the OpenGL graphics drawing library, and the byte stream input/output (I/O) model originated by Unix and adopted by MS-DOS, Linux, and most other modern operating systems.