What is a reach in foul in basketball?

Answer 1

Reaching in is not a foul. The term is nowhere to be found in any rulebook. There must be contact to have a foul. The mere act of reaching in, by itself, is nothing. If contact does occur, it's either a holding foul or an illegal use of hands foul. When a player, in order to stop the clock, does not make a legitimate play for the ball, holds, pushes or grabs away from the ball, or uses undue roughness, the foul is an intentional foul.

Answer 2

A "reach in foul" is when a player tries to steal the ball from his opponent, but draws contact with his opponent while attempting to steal. If the player makes no contact, there's no foul.