How would an audio engineer explain how reverb is created?

Answer 1

Reverberation can be created using several different techniques. There used to be dedicated rooms called "Echo Chambers" that naturally created the reverb. A loudspeaker would be placed in the chamber and play the audio, which was then recorded again by a microphone.

Other devices such as plate and spring reverb systems use contact microphones or pickups to record the reverb off of the vibrating component.

Nowadays, digital reverb is the most common application, where signal processing algorithms are used to create and control the effect.