As you advance in your bass lessons, you will begin song analysis on jazz tunes, because these tunes tend to be the most harmonically complex. When we analyze tunes, what we are attempting to do is to determine the key that we are in at a given moment in a tune, and find out what role the chords have in that particular key.
Jazz tunes tend to change keys quite a bit, which is why jazz gives us a sense of being “all over the place.” Pop music tends to be much simpler in a harmonic sense, as pop music tends to stay fairly close to one key center. A jazz tune on the other hand may change keys every bar, or sometimes two or three times in the same bar. Our job when we are analyzing tunes is to be able to see the key areas and identify them quickly, so we can create strong solos and bass lines that really outline the keys and the chords in those keys.
When we analyze jazz tunes, we will learn to look for key area, (blocks of chords that are in the same key.) We will write in our analysis on the chart, and through this practice, we will begin to see the patterns that emerge in jazz (and in all western music) over and over again. Pretty soon, a tune will not just look like a bunch of unrelated chords on a piece of paper, but a logical construct that we are able to identify quickly, allowing us to create strong bass lines and solos on the fly.