An interface may refer to any of the following:
1. When referring to software, an interface is a program that allows a user to interact with the computer or another computer over a network. An interface may also refer to controls used in a program that allow the user to interact with the program. One of the best examples of an interface is a GUI (Graphical User Interface) and is what you are using now to navigate your computer and how you got to this page.
2. When referring to hardware, an interface is a physical device, port, or connection that interacts with the computer or other hardware device. For example, IDE is a disk drive interface for computer hard drives and ATAPI is an interface for CD-ROM drives.