This is an excellent article on what master recordings are and a large fire that destroyed thousands of them in 2008.
Universal played down the musical devastation of this 2008 fire. Valuable recordings lost: Elton John, Nirvana, Coltrane, Tupac and thousands more https://t.co/CwORSrC1LO
In the newsletter today, @jodyrosen writes about how he got the Universal music fire story. (The answer is documents, it's always documents.) https://t.co/9yvbXCcMdZ