Flip-Flops are the most basic digital element that can store information. They are critical to modern computers.
Every modern computer uses a digital clock to regulate timing and execution.
Demultiplexers are the exact opposite of multiplexers. They take an input and connect it to one of many outputs.
Multiplexers allow for selecting a single signal from a group. They are critical to computers.
Logic gates are the first level of hardware abstraction when building a computer.