You’ve probably heard it by now. “Despacito,” the 2017 smash hit, has hit the charts in nearly 50 nations, including an unparalleled stint in the Top 40 in the United States for a Spanish-language song. It has now surpassed Wiz Khalifa and Charlie Puth’s “See You Again” as the most viewed and liked YouTube video of all time, becoming the fastest to reach 7.7 billion views and the first to hit 3 billion in just six months. Without a doubt, we’ve been singing and dancing along for much longer.

“Despacito” might be seen as a successful genre, rendering reggaeton even more accessible to the middle class, similar to what Juan Luis Guerra achieved for bachata in the 1990s. The efforts of Daddy Yankee, an experienced pro like Fonsi and Ender and a hard-core reggaetonero — a veteran who has been rapping in Spanish over reggae beats since well before San Juan’s local genre had a name of its own — help to soften the rough edges. Yankee, who is best known for his 2005 blockbuster “Gasolina” (one of the few reggaeton songs to chart in the United States), contributes his street cred and pop expertise to the proceedings, featuring a scorching verse and refrain that carry the song’s second half.

But first, let’s talk about chords. Reggaeton isn’t noted for its harmonic content, and “Gasolina” is powered by a simple alternation of semitones, which isn’t exactly Tin Pan Alley material. In contrast, “Despacito” employs four of the most popular chords in popular music over the last century. More exactly, the song adopts a chord ordering and arrangement that has been absolutely ascendant since the millennium’s turn. “Despacito’s” tried-and-true harmonic progression is crucial to its popularity.

While I don’t believe in a single magical explanation for “Despacito’s” extraordinary success, there are a few key variables to consider if we’re interested in learning more about this watershed moment in American and global popular music.

The first is simple but important: it’s a good pop song that combines decades of songwriting experience, a powerful chord progression, imaginative performance by experienced pros, and access to a worldwide music market. The second aspect contributes to “Despacito’s” ability to break out of the Latin pop realm and into the English and global markets: audiences were poised to accept a pop-reggaeton song in the middle of an ongoing and unabated craze for “tropical” sounds. While either of these two criteria could have applied to other periods in pop history, the third factor is the one that most obviously places “Despacito” in the early twenty-first century: YouTube.

Taken together, these elements reveal “Despacito” to be a multifaceted, deeply communal phenomenon that harkens back to the past — whether Tin Pan Alley, San Juan, or Kingston — as well as forward, to a world reinventing global pop in its own image.