I find it easier to define what it isn't.

It isn't a contest. Not for speed, or complexity, or attention, or technique.

Practiced individually, it's useful to think of it as a craft. If you want to learn a craft, seek out masters and pay attention to what they tell you and show you--even if it isn't always comfortable for you. Most people don't like being told the way they're doing something is all wrong--and it may not be, but listen and try before you decide to just do it your way.

Also very importantly, music is a sharing with others. That part of the craft involves learning how to use your own voice (including your instrumental voice) in a harmonic fashion with other people. There is give and take, talking and listening, soloing and backing up, an appreciation for sonic highs and lows. In my life, shared music is the highest form of communication; for this cranky old atheist, it is one of the two important spiritual experiences (the other one is being alone in a natural environment). Developing the craft is kind of like learning a set of religious rituals: once you know them, the mechanics are second nature. A musician won't play an out-of-tune instrument any more than a cabinetmaker would use a dull plane.

Cause everyone knows music is love.

Bill