Okay. I've searched for it but can't find any definite information. I'm really confused about the concept of chords. I know that, by rough definition, chords are three or more notes played simultaniously (sp). Pianos and guitars use them all the time. I get that part. I also understand generally they are made from notes in the same key, as in I-IV-7 intervals, for example. What I don't get is how they are applied to the bass guitar. Generally speaking, bassists don't usually play more than a single note (string) at a time. But I always hear about playing chord progressions and how important the difference between major and minor chords are and so forth. As far as I can tell, the bass player plays the root note of the chord, only. Maybe I'm mistaken, but I thought that was the purpose of the bass. What am I not understanding? (Obviously, I've mostly studied rock music, though I've had some training in jazz.) For example, if a guitarist plays all major chords: E, D, E, C; wouldn't the bassist play E, D, E, C notes? (I'm not sure I'm saying what I mean, as I'm not that versed in music theory.) Simply put, how do bassists use the concept of chord progression?