Years ago, I was listening to the radio when "Toxic" by Britney Spears came on. At the time I wasn’t particularly enthusiastic about admitting I was into a Top 40 pop song, but with "Toxic" it was a different story—I loved it and felt no shame about that fact. There are many great things here: check out that funky-as-shit bass line, the chunky guitar part and how the chords in the chorus build tension with that chromatic descending progression the first time (forgive a few music theory terms here), then release with the incredibly satisfying flat-six-to-five the second time, for example.

But for me the infectiousness of "Toxic" comes down to one primary element, the backbone of the whole song: a rhythm I’ve come to call the Magic Beat.