Applying different materials to one object?

So I made a very simple gun in unity consisting out of three cubes. (don’t worry I’ll be using blender the next time, this was just to follow a tutorial)

Now I’d like to apply different textures to the top and back of this gun, but if I apply a material it apply’s to the whole cube. So basicly I can only change the texture of the whole grip, the whole barrel and the whole middle-part (yes I have no idea how that’s called.)

Is it possible to apply multiple materials to one cube? And if it is, then how do I do it?

Much obliged,

Wim Naudts