https://www.youtube.com/watch?v=4B_UYYPb-Gk The original rap-rock mash-up, "Walk This Way" quite literally directed legions of hip hop heads and wannabe rock stars down the path to quality coalescence. "Walk this way," they said, gyrating their pelvises and swinging their gold chains, "and you'll be able to tap into two of the most divergent markets in the music industry at the same time." The crossover was equal parts rock mojo and hip hop flow, taking the best and most genuine parts of both worlds at a time when hair metal was all about the glamour (and not so much about the musicianship) and hip hop was still finding its footing. "Walk This Way" not only reinvigorated the dying, lifeless carcass of Aerosmith, but it gave Run-D.M.C. the opportunity to leave a huge imprint on the world of hip hop, defining its sound for years to come. Everything on the song worked, from the legendary vocal back-and-forth between the two emcees to Steven Tyler's cocksure delivery on the chorus. The instrumentation relied heavily on the original Joe Perry riff, but Jam Master Jay was also given some time to shine, tossing in a bit of record scratching, which was completely foreign to rock audiences at the time. Run-D.M.C. would go on to use heavy guitar riffs as a basis for a few other songs, like "King of Rock" and "Tougher Than Leather," but it never worked quite as well as it did on "Walk This Way." Still, it made electric guitars popular outside of mainstream rock, heavily influencing two of Michael Jackson's biggest songs, "Beat It" and "Black or White." It's nearly impossible to explain just how much this collaboration influenced pop music. The song became bigger than any of the individuals involved. It was a smash on the charts, but this is one instance where those numbers are completely underwhelming when compared to the legacy the song has left behind. To paraphrase Steven Tyler, those boys really "knew what they were doin'."