Why does my wrist pop when I rotate it?

Probably . Just the tendon rolling over the bone if there is no pain, swelling, or history of injury.
Ligaments. If your wrist pops without pain, do not worry. This could be ligaments or the wrist capsule which is responsible. If you have painful popping, see a hand doctor.

Related Questions

Why does my wrist pop when I rotate it? Why does my wrist and arm fall asleep really fast? And, Also, Why does my wrist feel like it is spazzing out?

Probably normal. Popping of joints in a young person is probably normal. Not sure what it means for the wrist to "spazz out". If the arm goes to sleep when it's being actively used (not just sitting still) then a medical exam would be needed to investigate further. Read more...