Hey man. So this was a really good question. We started off in the wax cylinder days of just using one mic direct to disc or film. We moved people around, changed the sound by different mic positions and mics, and eqs were invented in the 20s and were broad to make one mic sound like another than to correct sound problems. This lasted until the Germans developed analog tape. We, the English speaking world, had good RCA mics yet no idea how German radio broadcasts repeated themselves so clearly (we had... shellac lol) until we found tape machines in the rubble of World War II. Suddenly there was a canvas on which to process sound. You could bounce between two of them! And as tape machines got more tracks, more processing and more realistic recordings became possible. recordings have been multitrack since 4 track tape machines came out. Now we use a bunch of mics on different stuff and fit them together like a plastic surgeon. Let's start with mics, then a brief history of stereo recording, then basic processing, and current digital processing with both the typical ones that sound awful and the good ones and the unrealized potential of digital audio processing lost in a world of fleeting connections. I'll link posts here.