Most people are familiar with just a couple of kinds of door locks. Those include deadbolt locks and the basic pin tumbler locks. You probably have a pin tumbler lock in your exterior door. The lock is in the handle of the door. When the lock is turned, it generally keeps the tongue of the door's handle from moving from it's hole in the door frame. You probably also have a deadbolt. With a deadbolt, there is a bolt that gets thrown when you turn the thumbturn or the key. The bolt goes into a hole in the doorframe to keep the door from opening. But those aren't the only kind of locks. There are several other kinds out there. 

Wafer Lock

Instead of having pins inside the lock that are used to open the door, these locks have a series of wafers. It works in the same basic way that a pin tumbler works. The key has a series of cuts in it that move the wafers so that they are raised to the right height to open the door. One difference is that the wafers are made out of just one piece. Most pins are generally at least two pieces. These locks run the range of high security down to low security. However, most of these locks are on the lower security end. That means they aren't necessarily the best choice for an exterior door, but would work reasonably well for an interior door. 

Disc Locks

Disc locks don't use pins or wafers. Instead, they have a series of discs to open the lock. When the key is placed in the lock, it fits into the right section of the discs, which then allows the discs to be rotated so that the lock opens. A key for a disc lock doesn't look like one that goes into a pin tumbler or deadbolt. Instead, the key has cuts that are angled. So the key itself is a round cylinder that has sections cut out of it. Those sections correspond to the discs. It is slightly harder to pick a disc lock. That's partly because lock picking tools aren't commonly found. Most people who would try to pick a lock to get into a house won't generally carry the right picks for these locks because they aren't commonly found on doors. 

There are so many different kinds of locks out there. While all of them will work to keep a door locked, there are some that are much more secure than others. Also, even the most secure locks may be bypassed, given the right tools and plenty of time. If you want to get a very secure lock, talk to a locksmith, like those at Bellows Locksmith, to see what they suggest.