In 2004, Ciara went platinum. So did JoJo. As did Incubus. And Good Charlotte. And Big & Rich. And two Nelly albums -- neither of which contained "Hot in Herre," "Country Grammar" or "Ride Wit Me." And three different editions of "Now That's What I Call Music." Overall, not counting best-of releases, soundtracks or the "Now" compilations, 41 albums went platinum (the industry designation for 1 million units sold) that year, according to the Recording Industry Association of America's database.

In 2014, there were only two: Taylor Swift's "1989" and Sam Smith's "In the Lonely Hour." Yes, the industry has massively changed in a decade -- iTunes was still just a bit player in '04, and streaming music services didn't exist yet -- but it is still (barely) possible to sell a million albums in an age of singles. How did Swift and Smith do it?

Cross-Generational Appeal

The pop of Taylor Swift is music that parents don't mind listening to with their kids. The "crooner-chic" of Sam Smith is music that kids don't mind listening to with their parents. There's still appeal to songs that can reach everyone in a room.

Be Everywhere

Smith performed on "Saturday Night Live," "The Tonight Show with Jimmy Fallon" and the MTV Video Music Awards, among countless other stops, in 2014. Swift was inescapable as well, whether it was expert-level social media interactions with fans, her stint as an "advisor" on "The Voice" or her performance on New Year's Eve in Times Square. Never turn down an opportunity.

Be Yourself, Loudly

Both Swift and Smith are the primary songwriters on their albums. Swift's "1989" takes on critics who think Swift writes too much about ex-boyfriends and anonymous "haters," among other topics, while Smith's "In the Lonely Hour" centers on a young man's search for love and the early heartbreaks that follow. Both are unapologetic glimpses into relatable lives -- the perfect ingredients for beloved pop music.

IF YOU GO: Sam Smith performs at Madison Square Garden tomorrowThursday at 8 p.m., 4 Penn Plaza, 212-465-6741, sold out.