How do you tell if there is concrete behind drywall?
Then, how do you know if wood is behind walls?
A good starting place is 16 inches from a corner. For better precision, use a tape measure and mark 12 inches, 16 inches, and 24 inches from the corner. Tap the wall at each distance. You'll hear a solid sound when you tap the part of the wall that is supported by a stud.
In this way, what is behind a drywall?
Drywall is the rigid gypsum-based board that forms most walls in homes. Often called wallboard, drywall is usually 1/2-inch thick. It is either screwed or nailed directly to the wall studs.
Use a toggle: If there simply aren't any studs where you want to mount the TV, then you need to use some sort of hollow wall anchor. Mounting a TV on drywall or plaster without attaching to a stud can be a very safe and reliable solution IF you know the limits of the wall and the toggles.