was a monster hit, and for good reason. It was backed by live instruments, which gave the song elasticity and warmth. The groove was deep, funky, and Southern-fried; the lyrics gritty and descriptive without being dumb or exploitative—perhaps because they really had run the streets, Dre and Big Boi saw no reason to wallow in the gutter. Most important, they were serious musicians: They could sing without straining, and their delivery was unlike anything anyone had heard before.

But if the delivery—which combines smooth Southern drawls with sharp, staccato phrasings, and marks all OutKast's subsequent records (click here for a sample)—was unique, it was hardly the only thing that set the group apart. Never having entered rap's authenticity sweepstakes or based their identities on anything but their abilities, Dreand Big Boi found themselves free to evolve in ways other groups couldn't and soak up influences others ignored. They could sound like Marvin Gaye one minute, Dr. Dre the next, shift effortlessly between the two, and still sound unmistakably like themselves. On their second release, ATLiens, the beats were slower and jazzier and occasionally dropped out entirely while the rappers' voices soared over the gap. On their next two records, Aquemini, and Stankonia, OutKast took over production duties, expanded their palate to include acoustic guitars and harmonicas on the one hand and dense, techno-inspired textures on the other, and sharpened and quickened their delivery almost to the point of scat-singing (albeit with syllables that made sense on the page; here's a clip).

Nor were the group's lyrics typical: