i believe hot keys are keys you press to do something. like for example i will use vent because its the easiest to describe. the hot key to activate your mic on vent is left tab usually. if you hit left tab it will activate your mic. so they are a key you hit to activate something. another example might be like a macro. if in halo you hit the talk button then you hit lets say 9 then the macro you made will be typed out with a single hit of a key. i believe that i what they are.