Repertoire, the songs we play and how we play them. A song is a vehicle of self-expression. So whether playing your songs or other people's songs. It's all about the song.
There are four elements of a repertoire regardless of your chosen instrument.
Single Note Melody
Melody is the most recognizable element of a song. Without the melody, anyone would be hard-pressed even to identify what song it is.
The famous late, great jazz guitarist Joe Pass once said to a guitar player asking what to learn. Said "Learn melodies - no one goes around whistling chord progressions."
Background or Accompaniment
These are the chords that support the melody. Players use their chord knowledge and rhythmic sense to create effective accompaniments for melodic instruments, singers and improvisers.
Melody and Chord
This is the technique of combining the chords and melody of a song or composition. It is unique to jazz and ultimately requires an extensive chord vocabulary and a firm grip on harmony – the how chords work together.
The ability to solo over the changes – the chord progression.
Improvisation has been a hallmark of jazz. Improvisation is created by drawing from four sources: scales, arpeggios, intervals, and sequences. What brings a lot of musicians to play jazz is this improvisational aspect of the style. The spontaneous composition or combustion, at times of creating music on the fly.