Jazz Form

There's a lot of forms in jazz:

Twelve-Bar Blues

One common one is 12-bar blues, one example is:

I I I I | V V I I | ii V I V ||

There's a lot of alternatives too like:

I V I I | V V I I | ii V I V ||

General Form

Instead of using these chord symbols we group sections with letters:

AABA (each of 8 measures)

There's also variations of this too:

ABCA, ABAA, ...

Chorus & Head

A chorus is one time around the chord progression. Here AABA is the "head" (ie: the starting chorus). The second chorus might be a trumpet solo, the third a piano solo, then the ..., then the seventh chorus you play the head again to tie it together.

You can usually always count on the AABA structure (or whatever is decided on) for the solos themselves!