Tag
Tag is an added section of music that helps finalize the performance of standards or even jazz tunes. Usually referred to as "tag ending" by jazz musicians. In the classical world, the term coda is usually employed to describe this concept.
The harmonic and melodic material found in common tags is drawn from the last few bars of music in the tune and is repetitive in nature. A good rhythm section can usually "wing" a decent tag by repeating the jazz chords of the last 2, 4 or even 8 bars or the song.
This is how jazz musicians create a "coda".
Here's a common example of repeating the melody and the chords from the last few bars of music on a jazz standard.
To end the tune "Days of Wine and Roses" in F, we proceed to repeat bars 29-30 three times before ending on the tonic chord. Like this :
Sometimes, the tag can be used as a whole new section to improvise over before definitely ending a piece : the rhythm section "loops" the chord changes of the tag and the soloist keeps on improvising (until everyone feel it's time to end the piece, on cue).