Joe pass was a great Jazz guitarist and one often listened too by friend Emilia Nedzi and other people I know. Comping is the way to describe the guitar-playing behind a singer’s voice, so you see a Jazz guitarist and a singer as a duet what the guitarist does whilst the singer is singing is known as comping. Pass-frequently did this with Ella Fitzgerald.
It’s a great art to master and when you wish to make your playing sound colourful. In Jazz understanding chord harmony and chord relationships is imperative. Joe pass did just that, he knew how to blend in different chords with the singer’s voice. This was a skill which he had worked hard to accomplish. Guitarist like Ted Greene has mastered this style and have excellent books written on chord theory. I recommend his famous book chord chemistry. Brian Setzer the lead singer and guitarist from the Stray Cats studied Jazz guitar and was very good at utilizing this technique.
Jazz musicians are generally well trained as it’s hard to be able to play it and sound good with little knowledge so they all have to practice on a daily basis.