Many panned out: Iggy Azalea had a literally historic summer. Ariana Grande scored three big singles. Charli XCX became a household name. 5 Seconds of Summer helped buttress One Direction's highly successful ticket-selling stronghold.
There are also some artists we could have looked at and gone, "ehhh..." Mariah Carey has had a rough go for the last three years. Robin Thicke wrote his destiny when he named his album "Paula." Justin Bieber didn't kick off his 20th year on this earth with great acclaim.
In the slides below, we point out some of what worked and what didn't some we couldn't tell was coming. Who'd heard of a little band called Magic!, for instance? How about that first No. 1 album from Tom Petty? And, whoa, how 'bout that Weird Al?