Door securers are devices used to protect a door from being opened without permission. They come in many forms, such as locks, deadbolts, and chains. Locks are the most common form of door securer, and they are typically made of metal and have a key or combination that must be used to open them. Deadbolts are another type of door securer, and they are usually installed on the inside of a door and require a key to open them from the outside. Chains are also used as door securers, and they are typically used to secure a door from the inside. All of these door securers provide an extra layer of security to help keep unwanted visitors out.