In the context of computer terminology, the word gateway is used broadly to apply to the link or bridge between two separate systems or programs, and which serves as a portal between which the disparate programs can share data and information by facilitating communication between various protocols on a computer, or between two different computers.

There are many common examples of gateways in common usage, including gateways that connect systems like email clients to news servers, gateways that enable message boards and forums to pull data from feed aggregators, and gateways that permit an external resource to draw on the functions of multiple and separate native applications.

Gateway programs serve the crucial function of permitting interactivity between and integration of multiple applications from different vendors, overcoming interoperability issues that prevent these applications from being used together directly. Through a gateway, functions from multiple applications can be integrated for use by an external resource – for example, a gateway instant messenger program that allows users to control separate ICQ and Skype accounts from the same local and central interface.