What makes for a classic rock song? Oftentimes, a rock song features three or four chords in a basic progression, played fast and with an attitude. It often has simple lyrics, suggestive lyrics, or sometimes lyrics that just don't make any sense. But all of these come second place to The Riff. The riff frequently begins the song and reoccurs throughout it, giving the song a distinctive voice. But even the riffs are all very unique. Some are simple, some hammer out loud and fast demanding your attention, and some are intricate and surprisingly beautiful. Or in the case of Jimi Hendrix and some others, it can be all three. But I digress. Today, we will be looking back through rock history and discussing what riffs have had an enduring legacy, which ones have influenced other musicians, or are just plain awesome. Note: There is no scientific formula for determining this list, neither would it be possible for this list to please everyone. We'll be analyzing these riffs in chronological order, beginning with 1958....