cracking your knuckles

[SFDMALEX]

You are simply releasing the gas buildup in your joints. Which is a good thing. And long term prevents arthrites.

It just depends the extent to which you do it. If you bend your knuckles or other joints too much when you are "cracking" then you may overstress your ligaments and muscle, and grind bone which is NOT GOOD. So you have to know how much is too much.