A child safety lock is a special-purpose lock for cabinets, drawers, bottles, etc. that is designed to help prevent children from getting at any dangerous contents. Young children are naturally curious about their surroundings and will always explore, but as they may be unaware of dangerous substances or situations, the results can be fatal. Numerous cases of poisoning have resulted from eating brightly colored pills or spilling cleaning solvents.
In the United States, child safety locking mechanisms have been required by law since 1970 on all containers for potentially dangerous medicines and household cleaning products. These laws are enforced by the Consumer Products Safety Commission. These locking mechanisms may take several forms, but the most common is a design that requires a tab to be pressed firmly as the lid is twisted. Great strength and dexterity are not required to open the bottle, but the process is deliberately made to be unintuitive, and the children who might recklessly eat pills are unable to decipher the opening instructions. Parents and guardians are firmly admonished  to keep all such containers out of the reach of children anyway, as no locking device is foolproof. It has become common practice in households to keep medicines and pills in high cabinets (sometimes locked) for safety. Cleaning agents, however, are still generally kept under sinks, where they are accessible.
Another type of lock is an inexpensive device which can be easily installed into drawers, cabinets, or other openables to prevent easy opening. It consists of a bendable plastic rod with a blunt hook on one side, and is situated on the inside of the drawer or cabinet. The hook catches on part of the drawer or door and prevents opening unless the rod is bent downward simultaneously to disengage the hook. These devices are helpful to pet owners as well -- a typical housecat may be able to paw open a cabinet filled with food, but would have trouble operating the hook mechanism. Also available are electromagnetic cabinet locking devices that are activated via remote control.
Child safety locks are built into the rear doors of most cars to prevent rear seat passengers from opening the doors both during transit and while the vehicle is stationary; vehicles have been built with this feature since the early 1980s. They provide the vehicle driver with a simple, safe & secure method to prevent unauthorized exit from the car. Although called a child lock it is equally effective for adult passengers.
The lock is typically engaged via a small switch on the edge of the door that is only accessible when the door is open. Some cars implement the child lock control as a rotary mechanism which can only be operated with a key. This design ensures the child lock remains in its intended state, it is invaluable for older children or adults that may tamper with the lock when the door is open. Once the door is closed, control of these two mechanical type child locks is completely inaccessible to the passenger. In some newer models the child lock can be activated electronically from the driver position via a Door control unit, (Volvo V40 owners manual).
When the child lock is engaged, the interior handle is rendered useless, usually just moving freely without unlatching the door. In this state the passenger simply cannot open the door, nor can they disable the lock, and are effectively locked in. The door can only be opened by someone lifting the outside handle, either a second person or by the passenger opening the window and reaching the outside handle.
Child safety locks can be fitted to pool fencing in order to make a pool area safer.
In Australia, pool fencing is required by law. It is stipulated that the lock should be attached on the side of the fence facing toward the pool, so that anyone entering would have to reach over the top of the boundary. Failing this, the child safety lock should be at least 1.8m off the ground.