When I was a sophomore in College I had a summer job assembling designer lamps. The "factory" (I was the only employee) was located among a strip of small storefronts along Brighton Avenue In Allston, Massachusetts. It was two doors down from a small record shop called Uncle John's Records where I used to spend a percentage of my weekly paycheck on Friday after work.
While it may be hard for you young 'uns to imagine, but there once was a time, before Virgin and Tower Records, when record shops used to dot the land. Many were like Uncle John's - small, one-owner operations that were as quirky as their owners.
Uncle John's had a special section, hidden in back, behind the curtain that separated the public from the private part of the store with John's bed and hotplate, that held "bootleg" records. These "bootleg" records were usually illegal, unauthorized pressings from live concerts and studio outtakes. At that time bootlegs were the primary target of the RIAA's anti-pirating efforts. And, much like today, these efforts were largely an unsuccessful fools' errand.
The most famous "bootlegs" were titles from Bob Dylan. The Basement Tapes and The Great While Wonder filled the several-year gap after Dylan's motorcycle accident and the release of Nashville Skyline. Some songs, such as "Quinn the Eskimo" were only available via this recording. Finally, in 1975 Columbia released the "official" version of the original bootleg, in the same year that Blood on the Tracks came out.
Other popular bootleg subjects were the Rolling Stones. I still have one Rolling Stones bootleg titled Live R Than You'll Ever Be on the outer jacket and Live: In Again Out Again on the record label itself. Produced by Oakland Records, the disc is a live concert recording taken from the same tour as the official Stones release, Get Your Yaya's Out, with most of the same songs. But the versions of the songs are from different takes than the legit version. Mick Taylor's timing on his slide guitar solo during "Love in Vain" is far better on the bootleg than on the official release - every time I hear the authorized version I long for the "right" solo on the bootleg.
One more thing about bootleg LPs - they were expensive. While a standard disc was around $4, most bootlegs were at least $10, most $25, and some, like The Basement Tapes cost upwards from $50 to as much as $200. Also the quality of the pressing, recording, mastering, and even the vinyl itself on many bootlegs was atrocious. Try before you buy was usually not an option. I remember a Jimi Hendrix Bootleg, where the surface noise was so bad it sounded like it was recorded in a popcorn factory.
As to how many bootlegs I still have in my record collection, I'm going to plead the 5th. Most vanished over the years, but when I want to hear what I still consider the best version of the Rolling Stones performing "Love in Vain" live I reach for the version in the distressed plain white jacket...