What are Armor Check Penalties?
The penalty to movement-based skills you receive if you are using certain armors or shields. The movement-based skills are Balance, Hide, Jump, Move Silently, Swim, and Tumble. Note that Swim, due to the nature of the skill, takes double the penalty. Also, if you are not proficient with a piece of armor or shield, you will take the armor check penalty on your attack roll as well as on your movement-based skills.
