Triplanar projections work with a Triplanar maps. It takes the coordinates in world or object space and picks the projection axis depending on the active axis of the Triplanar map. This gives a quick way to map a Texture on any Object, and presents the possibility for Texture transforms local to each projection axis. Triplanar maps have six input pins representing the positive and negative X, Y, and Z planes. You can map the same or different Texture nodes to each of these input pins.
Figure 1: The Triplanar Map node and the Triplanar projection node mapping a Check texture and an imported Texture to an Object's different projection planes