The first type of security system ever made outside of keeping watch yourself, the concept of the lock and key has changed far less than the engineering and technology that helps it to happen.
The earliest locks yet discovered have been found protecting valuables in ancient Egypt and Assyria, and for the most part, the basic mechanical principle for locks and keys has not changed a great deal, although a new trend of smart locks may help to make them even safer.
Smart locks are a group of security system solutions built around ensuring your doors are safely secured and can sometimes act as an additional accessory to a traditional deadbolt lock or can sometimes replace it entirely with an alternative authentication system.
In most cases, this takes the form of a keyfob or smartphone app that authenticates the person trying to enter, and in other cases can be a keypad or a touchpad.
What makes them so appealing is that there is a lot more control over when someone is and is not allowed to unlock the door at a particular time.
For example, for housesitters, babysitters or delivery staff who need only temporary access, they can be provided with a keyfob or temporary access that can be revoked whenever the owner chooses or set to only activate at certain times of the day.
This can make them especially useful in offices where they can be coordinated with shift patterns.
As well as this, smart locks can be controlled remotely if they have Wi-Fi connectivity, meaning that you can unlock the door for someone even if you are far away.
It should be noted, however, that smart locks are generally connected to deadbolts and so they are only as secure as the door they are connected to.