English is not my native language and I do not understand why the words "shift keying" were used to describe some types of digital modulation.
What does "keying" mean in the context of signals and modulation? I know what a key is: something that unlocks a door or a password but I have no idea what does the verb "keying" mean in this specific context of modulation.
What do those words mean individually in this context and what do they mean together in this context?
My question is one about terminology more than about electronics. I understand what Amplitude Shift Keying (ASK) is now. What I do not understand is what is the meaning of the words "shift keying" and why this type of modulation was not named simply "amplitude modulation"?
In none of the Wikipedia articles that contain the phrase 'shift keying' and from the context I do not understand why were those words used. What I understand is 'moving a key' I do not know how is this related to modulation or to electronics in general.