Emulation is the ability of a computer to run programs intended for another computer platform. Since not all software is available on all computer platforms, emulation provides the ability to mimic other platforms from a single computer.

The use of emulation occurs through an emulation session. An emulation session is a real-time interactive session that mimics the look and provides the same functionality as the true system. An emulation session requires installation and configuration of software that tells the computer how to connect to and emulate another system. Different software or drivers are required for each type of system being emulated.

Terminal emulation is one of the most common types of emulation. Terminal emulation allows PC users to connect to a mainframe system (or other system with a proprietary connection) as a dumb terminal. The terminal emulation session runs within the operating system of the PC and allows users to work with both mainframe and PC-based applications from the same computer.