In communications or computer systems, a configuration of a system refers to the arrangement of each of its functional units, according to their nature, number and chief characteristics. Often, configuration pertains to the choice of hardware, software, firmware, and documentation. Along with its architecture, the configuration of a computer system affects both its function and performance.

The configuration of a computer is typically recorded in a configuration file. In modern computer systems, this is created and updated automatically as physical components are added or removed. Applications may assume that the configuration file is an accurate representation of the physical configuration and act accordingly.