The set of variables and functions used to communicate between different parts of programs.

See Also: Application Binary Interface.

A technical description of how the operating system should interface with hardware.

See Also: Application Programming Interface.

Some reasonable definition here.

See Also: Standardised Generalised Markup Language.

The grand daddy of all documents

See Also: Extensible Markup Language.

When a number of things are mutually exclusive, only one can be valid at a time. The fact that one of the things is valid makes the others invalid.

Software distributed in source form under licenses guaranteeing anybody rights to freely use, modify, and redistribute the code.

The interface used to interact with the operating system.