Short answers, pulled from the story.
The term record label derives from the circular paper label at the center of a vinyl record, where the manufacturer's name and other information appeared prominently. This physical label gave the entire industry its name.
The Big Three are Sony Music (founded 1929), Universal Music Group (founded 1934), and Warner Music Group (founded 1958). By 2014, their combined global market share was estimated at 65 to 70 percent.
The consolidation happened in stages. PolyGram merged into Universal Music Group in 1999, reducing the Big Six to the Big Five. Sony and BMG formed a joint venture in 2004, creating the Big Four. In 2012, Citigroup sold off EMI's divisions to Universal, Sony/ATV, and Warner, leaving the current Big Three.
A 360 deal, also called a multiple-rights deal, gives a record label a percentage of an artist's income from touring, merchandise, and endorsements, not just recorded music sales. In exchange, labels typically offer higher advance payments and a larger share of album profits, sometimes 30 percent compared to the typical 15 percent royalty.
An imprint is a brand or trademark used by a parent label without existing as a separate business structure; it typically functions as a pseudonym for the parent company. An independent label is a separate entity not controlled by one of the major music groups, even if it is sometimes distributed by a major.
Artists who have had disputes with labels over ownership and control include Taylor Swift, Kesha, Prince, Paul McCartney, Johnny Cash, Kanye West, and Kelly Clarkson, among others. Prince's conflict with Warner Bros. Records lasted from 1994 to 1996, and Roger McGuinn testified before a US Senate committee in July 2000 that the Byrds never received royalties for their biggest hits.