What is a legal check in hockey?

Answer 1

You can check at any speed anywhere on a player except you can't check them from behind and you cant check them when they are near the boards because you will get a boarding penalty. You are allowed to check them if they are along the boards though.
You can do an open ice check which is when you check someone who is out in the open. But you are only allowed to check with your hips, torso, and shoulders. you are not allowed to raise your arms and you are not allowed to push with your hands and you definitely not allowed to kick.