Type: General
Source: Player's Handbook
You are proficient with light armor (padded, leather, studded leather, chain shirt).
Benefit: When you wear a type of armor with which you are proficient the armor check penalty applies only to Balance, Climb, Escape Artist, Hide, Jump, Move Silently, Pick Pocket, and Tumble checks.
Special: All classes except wizards, sorcerers, and monks automatically have Armor Proficiency (light) as a bonus feat. They need not select it.
Normal: A character who is wearing armor with which she is not proficient applies its armor check penalty to attack rolls and to all skill checks that involve moving, including riding.