Before we were able to share songs online, there was something called tape-trading.
Fans of a particular band or genre would connect at shows or through the back pages of music magazines offering to trade cassettes of demos, live shows or rare recordings. Once the connections were made, most of the trading happened by old-fashioned snail mail. The result was a series of communities knitted together by these tapes.
The Grateful Dead was probably the first to actively encourage their fans to trade tapes. Everything had to be done for free. Charging for these tapes was considered highly uncool and frowned upon.
Tape-trading did wonders for metal, too. Metallica fans were big tape-traders.
Then there was the punk community. For example, LA hardcore tapes made it up to Seattle where they helped create the foundations of grunge. Yes, it was all very risky from a copyright point of view, but the benefits to everyone far outweighed the risks.