Locksmiths are trained to pick locks. Sometimes people get stuck out of their car or their house and need to get back inside. This is where commercial locksmith service are useful. Lockpicking is somewhat or an artform.
Most locks have imperfections that make lockpicking possible. In this video, you will see how one man attempts to make an unsolvable lock.
First, it is important that you understand how locks work. Every lock as several pins. Each pin must be pushed to the exact height to unlock the lock. This is why keys have notches in them. Each notch pushes each pin to the specified height. To pick a lock, each pin would have to be pushed to the correct height without keys. This can involve thousands of combinations. However, most lockpickers attempt to feel for each pin to get caught one at a time. This makes guessing much easier.
The person in the video attempted to make an unsolvable lock by making it so the lockpicker must guess all pins at once instead of one at a time. This would make it nearly statistical impossible to guess. To do this, he used machines to custom make his own lock where each pin can not be picked individually.