what is Ground/Car body?

[mark0101]

Red Wire - Connect to the Reversing light positive feed.

Black Wire - Connect to a negative power supply (Ground/Car Body).
I am trying to install parking assist system on my car but I don't know where to connect the black wire
so what is Ground/car body?
thanks in advance

 

[Jibit]

connect it to a metal piece that is connected to the frame of the car, where is the wire at?

 

[mark0101]

Oh nevermind, I found it. I was trying to install backing up sensors on my Continental. The positive and the negative were in the same spot.