Combination and key-based padlocks are some of the most common locks available. Unfortunately, these are fairly easy to pick or break, which is reflected in their price. Though they are not typically used on residential doors, they are highly portable and can be used as a temporary solution, or in combination with a sliding bolt latch to lock a shed or garage, for example. Padlocks can be combination-based or key-based, and some are key-retaining so that you cannot remove the key while it is unlocked.

These popular door locks operate with a key from the outside and a thumbturn on the inside. A flip guard, which prevents the lock from being picked and unlocked from the outside when enabled, can be installed around the thumbturn for added security. Single cylinder deadbolts are frequently used in combination with a keyed door knob or lever handle on exterior doors. These locks include Euro Profile Turn Cylinders, and can be developed to various security standards. See Schlage’s variety of single cylinder deadbolts, for example.

Double Cylinder Deadbolts are considered to be more secure than their single cylinder counterparts because they are operated using a key on both the inside and outside. This type of lock can pose a safety hazard in emergencies as the exit will be obstructed without a key, which is certainly a factor to consider, especially if you have children. offers various brands including Era, Yale, Cisa, and Iseo.

The lockable thumbturn style lock is best described as a hybrid of the single and double cylinder deadbolts. The lock is operated with a key on the outside and a thumbturn on the inside like a standard single cylinder deadbolt. However, the thumbturn can be locked with a key from the inside so that the lock cannot be operated from either side until the thumbturn is unlocked. Though not very popular or widely available, these locks are highly secure.

These are two different types of hybrid cylinder locks with much in common. They are considered more secure than standard deadbolts, and therefore frequently used in commercial and apartment settings.

Mortise locks require a pocket (the mortise) to be installed inside the door frame to contain the locking mechanism. If the lock includes a non-locking sprung latch operated by the door handle it is known as a sash lock. The simpler form without a handle or latch is known as a deadlock. The latter is commonly used as a secure backup to a sprung non-deadlocking latch. See Era for their variety of mortise locks.

Rim cylinders, on the other hand, are used with surface mounted locks operating from a tailbar, ie nightlatches. They have a long tailpiece that extends from the tailpiece (keyhole) through the door and into the locking mechanism on the other side.

The jimmy-proof deadbolt is a variation on the standard deadbolt. It is sometimes referred to as a Segal lock, after the company that first designed it. It is mounted on the surface of the door, requiring minimal modification to the door during installation. It is commonly used on double doors and apartments for this reason. It is most popular as an added security feature in addition to a more traditional door lock. This type of lock is characterised by a deadbolt which interlocks with the jamb bracket, making it much more resistant to excessive force than a standard deadbolt. One company that sells such locks is link.

As digital and smart technology advances, so do locks. Digital locks have been used in cars and hotels for years, but are growing in popularity for other applications as well. They are designed to be operated using a key code or swipe card. They can take a wide variety of forms.

Smart locks are a step up from digital locks, and can be operated using a smartphone. The smart technology replaces the thumbturn element of a traditional lock, and allows you to operate the lock remotely. These are, of course, much pricier than traditional locks. Some brands that offer such modern lock technology include August and Schlage.