Sorry for not explaining well.
IsKeyPressed returns true just the frame when it has been pressed. The next frame, IsKeyPressed will return false, but IsKeyHold still returns true.
IsKeyHold is IsKeyDown.
It's pretty useful. Lots of games needs to check if a key is just pressed.
For example, you have a shooter game. You have a handgun and you want it to shoot every time you press Space (like shooting with a handgun in Counter Strike).
Edit: Forgey IsMouseMoving, it's pretty useless xD