There are locks that do not need a key to open them.. They are called combination locks.. To open these locks you have to match certain numbers and spin a disk in a certain way.. If the combination is D9, 17, D4, it means that you have to turn the disk to the right until it points to the point 9, then to the left to the point 7 and, Finally, turn right again to the point 4. Each turn of the disc causes the drums inside to be arranged in the proper position. When you've done the last lap, all you have to do is throw away. The door opens.
Closure with watch
Clock locks are like combination locks.. But they also have a watch. The door cannot be opened until the clock strikes the indicated time, not even if the combination is known.
String, latch and bar
A door can also be closed by running a latch, putting a chain, sliding a bolt or jamming it with a thick wooden bar.