An interface, also known as an interface, is the point of contact between two systems for data transmission. These systems can be both different hardware or software units, as well as the point of contact between man and machine. Interfaces enable data transmission. At the same time they also define the transition of different networks or programs. A simple example of everyday life for an interface is a socket that becomes the interface between a cable and the power grid. The data exchange between the systems is only guaranteed by the presence of an interface. They practically act as translators to facilitate the communication of data between the systems involved.

Interfaces of IT are available in the operating system, for example, and allow, for example, the access of a program to the hard disk. There are two types of interfaces: unidirectional and bidirectional. With a unidirectional interface, the data transfer takes place only in one direction. An example of this is the transfer of print data to a printer. However, most interfaces are bidirectional, so there is a data exchange in both directions. Examples of external bidirectional interfaces are e.g. the HDMI or USB port.
Today, more and more wireless interfaces are being used. Everyday examples of this include playing music on a device via a Bluetooth speaker or accessing the Internet via a WLAN.