A module may refer to any of the following:
1. When referring to computer software, a module is a discrete piece of code which can be independently created and maintained to be used in different systems. For example, a developer may create a module that contains the code required to use a sound card or perform I/O on a certain type of filesystem. The module can then be distributed for and used by any system that needs that functionality, and development of the module can proceed independently. This approach is known as modular design.
2. When referring to computer hardware, a module is an independent component that can be used as part of a more complex system. For example, a memory module can be connected to a computer's motherboard to operate as part of the complete system.