Now that we have some context, let's go layer by layer through the key components of 2019's butterfly switch:

Topping it all off is the key cap. This has a handy label to tell users which key is broken.

The hinged white bracket is the "butterfly" mechanism controlling the key's motion—stabilizing it so as to travel up and down without tilting or wobbling.

Nesting within that bracket is a transparent cover that flexes with each key press, while keeping contaminants away from the dome switch underneath. The black dot at its center concentrates the force of your key press onto the switch.

The main character of this assembly is the springy metal dome switch. It deforms when the key is pressed, bridging the board's six contacts—and then bounces back when you release the key.

Underneath the dome switch are six metal pads. A keystroke registers whenever the top center pad is shorted to any of the other five pads.

To wrap it up, the silicone membrane covers the butterfly mechanism to keep debris from getting in and jamming it.