Mirroring your PC's display on a multimedia projector lets you output the computer's display on both your computer's primary display and the large screen associated with the projector.

This post discusses wirelessly projecting and screen mirroring your Windows computer or laptop to an external display like a TV or a Projector using Miracast technology.

How Do I Project My iPad Screen for an Audience?. In addition to enabling you to check your email, watch movies or surf the Web, Apple's iPad tablet is also useful as a portable projection device.