Jazz is a crisp hard apple with an excellent strong sweet-sharp flavor, and a pronounced fruity pear-drop note.  The flavor undoubtedly puts it in the first rank of apples, and it is hard to think of a traditional variety that can compete with it.
Jazz  was developed in New Zealand in the 1980s. It is a cross between two other major apple varieties - Braeburn and Gala. 
Jazz apples often have an upright  elongated shape which is also somewhat reminscent of Delicious. Two other very significant ancestors are Cox and Golden Delicious. Whatever the genetic mix, the result is a great and unique apple.
The butter-yellow flesh is juicy, crisp and dense.