Mouse 1?

Hello, I downloaded a combat arms aimbot, and when i was gonna activate it it said : Activation key: Mouse 1 or mouse 2 or mouse 3.

What does mouse 1/mouse2/mouse3 mean???

Help pl0x!

there was a other activation thing to : unbind aimbot..

What does this shit mean??

Mouse 1 = Primary Click (normally left click)
Mouse 2 = Secondary Click (normally right click)
Mouse 3 = Wheel Button