Locks come in many types. Generally they are referred to as either being deadbolts or latch locks. Deadbolts are simply bolts that can be easily extended from the door into the jamb. Deadbolts come in several types and are usually installed separately from the latch.
A latch lock is always completely retained in the door, and a key is used to disengage the device from the locked or closed position. When not in use, the latch lock is always engaged in the closed position. Also, latch locks have pointed latch bolts compared to the dead bolts, which have a flat end. There is also a variation of the latch lock called the key-in-the-knob lock. Here the cylinder is located in the door knob instead of inside the door frame, but still the latch is always in the closed position unless the key is engaged. A key-in-the-knob lock is rarely found on an exterior door.
Generally both deadbolt and latch locks are installed by cutting a large circular hole in the door and then putting through a smaller-sized hole from the side of the door until it enters the empty space created by the large circular incision. A small hole is also cut into the jamb to house the deadbolt or latch bolt. A metal plate goes both on the inside of the door and on the face of the door jamb. These metal pieces are collectively referred to as a “lock front and strike plate.” The front and rear of the deadbolt lock are held into place by pressure from screws that pass through the body of the lock.
Most locks feature cylinders that operate when the key is engaged. In a deadbolt, the lock is often left idle or in the open position when it is not in use, while with a latch lock the locking mechanism is always engaged except when the key enters the cylinder and turns the latch bolt to the open position. If both type of locks are present on a door, the deadbolt must be opened first and left in the open position, then the latch lock can be engaged and the door opened.
Locks keep your house or apartment secure. They can also add some decorative function, but even the most decorative lock is not more secure than a well-made simple latch lock. Lock systems called “handle sets” are the most expensive locks, since they include both a dead bolt and a very fancy latch lock with a large metal plate that is activated by turning a key and pressing down on a handle. Despite their appearance, handle sets are not more secure than other combinations of locks.
There are several types of dead bolts: single cylinder, double cylinder and high security. The single cylinder has a key on the outside and a turn knob on the inside, while a double cylinder has a key operated mechanism on both sides. A single-cylinder deadbolt should not be installed on a door with a glass window. The high-security deadbolt has special pin configurations, and it is very difficult to get duplicate keys made for the device.