A padlock is one of the most common locks around, and it’s everywhere. They are locks with a shackle attached to add extra security to a building or environment. Padlock seals can be looped through a fence or chain to be even more secure.
Padlocks were mostly used by merchants as far back as the Roman era, and have become very popular in today’s world. The name Padlock came from the word paddock, which is where animals were stored during the Viking era. Soon the word pad was added to the lock and the word stuck.
The way a padlock works is by attaching the lock to a shackle, and not only does the key have to open the lock, but it also has to break the connection between the lock and the shackle. An integrated locking system connects the shackle to the tumblers inside the lock. With these, you needed the right key to not only turn the lock, but also to get the lock out of the shackle so you could open it.
Otherwise, getting inside with the proper key is much harder and forces would be thieves to break the lock, which takes time and has a higher risk of being caught. Modular locking systems also require a key but are not connected to the shackle. You still need the correct key to disengage the bolt and open the door, but you can lock the lock without the key.
Most household doors are modular locks, where you need the key to open the door, but you can lock the door from the inside without one. With integrated locks, you need the key to gain or refuse access no matter what. Padlocks have seen many different forms over the years, but they still continue to keep us safe, and likely still will.