Short answers, pulled from the story.
The first popular rock bootleg was Great White Wonder, a 1969 collection of unreleased Bob Dylan recordings. Bootleggers obtained a reel-to-reel tape of Dylan material, pressed between 1,000 and 2,000 copies at a local plant, and released the album in a plain white cover with the title rubber stamped on it.
The word bootleg comes from the practice of smuggling illicit items inside the legs of tall boots, closely associated with alcohol trafficking during American Prohibition. It became a general term for any unlicensed or illicit product, and was eventually applied to unauthorized recordings.
Bootleg recordings were prohibited under US federal law when the Uruguay Round Agreements Act took effect in 1994, under 17 USC 1101. The 1976 Copyright Act had earlier extended copyright protection to all recordings, including unauthorized ones.
Live'r Than You'll Ever Be, an audience recording of the Rolling Stones' late 1969 American tour, sold several tens of thousands of copies and received a rave review in Rolling Stone. Its success contributed to the official release of Get Yer Ya-Ya's Out! later in 1970.
Prince's The Black Album was pulled from release on the 1st of December 1987, just before its scheduled commercial launch, and 500,000 copies were ordered destroyed. A small number of advance copies had already shipped and became the source for a widely circulated bootleg, which preceded the album's eventual official release.
The Grateful Dead tolerated fan taping throughout their career and in 1985 formally endorsed live recording at their shows, designating specific areas for the best sound quality. They opposed commercial bootlegging and policed stores that sold recordings for profit, while the free circulation of tapes among fans suppressed commercial demand.