The earliest patent for a double-acting pin tumbler lock was granted to American physician Abraham O. Stansbury in England in 1805, but the modern version, still in use today, was invented by American Linus Yale Sr. in 1848.

To make a new key for an existing lock, you cut a series of notches in the key so that it raises each of the upper pins just above the shear line. Essentially, you cut a pattern in the metal that matches the pattern of the pins in the lock.

The blade is the specific part of the key which slides inside the lock. The bow is the portion which protrudes from the blade; the part you hold in your hand when you use the key. *Some of the keyways offered. A Kwikset keys, for example, will always fit in a Kwikset lock, even if it won't turn.

This simple tumbler lock was probably invented around 1000 BCE, although a date of 2000 BCE has also been proposed. Many sources believe this lock was invented in Egypt, though locks of this type have been found in ruins in Iraq that predate those found in Egypt.