The Lock Pick skill allows Bards and Rogues to open locked doors, chests, and other interesting things. The skill is most prominantly known for being a Rogue skill but Bards can become very proficient in using it as well.
You must have a set of Lockpicks in hand to use the Lock Pick skill. A basic set of Lockpicks can be purchased from certain merchants or created through the Smithing tradeskill. Special lockpicks with Lock Pick skill bonuses, such as the Mechanized Lockpicks, can also be purchased, created through tradeskills, or found throughout your travels.