The most common key type for residential homes and offices. They have serrated edges that align pins [1].
For centuries, warded locks remained the standard. However, they were incredibly easy to pick; a skeleton key with most of its blade cut away could bypass almost any ward. The Industrial Revolution changed everything, birthing the field of high-security mechanical engineering.
As computing power evolved in the late 20th and early 21st centuries, physical brass keys began sharing the stage with electronic code. Security shifted from mechanical physical alignment to data transmission. Magnetic Stripes and Keycards
“You see,” Mrs. Koval whispered, “keys are not for keeping people out. That is what everyone thinks. But a key is a promise that somewhere, there is a door that will open for you . Not against the world. For you.”