A latch or catch (called sneck in Northern England and Scotland) is a type of mechanical fastener that joins two (or more) objects or surfaces while allowing for their regular separation. A latch typically engages another piece of hardware on the other mounting surface. Depending upon the type and design of the latch, this engaged bit of hardware may be known as a keeper or strike.
A latch is not the same as the locking mechanism of a door or window, although often they are found together in the same product.
Latches range in complexity from flexible one-piece flat springs of metal or plastic, such as are used to keep blow molded plastic power tool cases closed, to multi-point cammed latches used to keep large doors closed.
Common types
Deadbolt latch
A deadbolt latch is a single-throw bolt. The bolt can be engaged in its strike plate only after the door is closed. The locking mechanism typically prevents the bolt from being retracted by force.
Spring latches
A Latch bolt is an extremely common latch type, typically part of a lockset. It is a spring-loaded bolt with an angled edge. When the door is pushed closed, the angled edge of the latch bolt engages with the lip of the strike plate; a spring allows the bolt to retract. Once the door is fully closed, the bolt automatically extends into the strike plate, holding the door closed. The latch bolt is disengaged (retracted) typically when the user turns the door handle, which via the lockset's mechanism, manually retracts the latch bolt, allowing the door to open. A deadlocking latch bolt (deadlatch) is an elaboration on the latch bolt which includes a guardbolt to prevent "shimming" or "jimmying" of the latch bolt. When the door is closed, the latch bolt and guardbolt are retracted together, and the door closes normally, with the latch bolt entering the strike plate. The strike plate, however, holds the guardbolt in its depressed position: a mechanism within the lockset holds the latch bolt in the projected position. This arrangement prevents the latch bolt from being depressed through the use of a credit card or some other tool, which would lead to unauthorized entry. A draw latch is a two part latch where one side has an arm that can clasp to the other half, and as it closes the clasp pulls the two parts together. It is fequently used on tool boxes, chests, crates and windows and does not need to be fully closed to secure both halves. A Spring bolt lock (or night latch) is a locking mechanism used with a latch bolt
Slam latch
A slam latch uses a spring and is activated by the shutting or slamming of a door. Like all latches, a slam latch is a mechanism to hold a door closed. The slam latch derives its name from its ability to slam doors and drawers shut without damaging the latch. A slam latch is rugged and ideal for industrial, agricultural and construction applications.
Cam lock
A cam lock is a type of latch consisting of a base and a cam. The base is where the key or tool is used to rotate the cam, which is what does the latching. Cams can be straight or offset; offset cams are reversible. Commonly found on garage cabinets, file cabinets, tool chests, and other locations where privacy and security is needed.
Electronic cam lock
Electronic cam locks are an alternative to mechanical cam locks. The appearance of the electronic cam lock is similar to the mechanical cam lock, but it is different in the lock cylinder.
The keyhole of a mechanical cam lock is usually the same as an ordinary padlock. A physical key is used to unlock the lock. The physical key has a notch or slot corresponding to the obstacle in the cam lock, allowing it to rotate freely in the lock.
Different from mechanical cam locks, electronic cam locks use an electronic key to unlock. The key needs to be programmed which contains the user, unlocking date, and time period. The electronic cam lock has no mechanical keyhole, only three metal contacts are retained. When unlocking, the three contacts on the head end of the electronic key are in contact with the three contacts on the electronic cam lock. At this time, the key will supply power to the electronic cam lock and read the ID number of the electronic cam lock for verification and match. If successful, the lock can be unlocked.
The emergence of electronic cam locks aims to improve the safety and functionality of traditional mechanical cam locks.