Jazz Core provides the basic rules for a generic, universal game system. It is assumed that Jazz Core will be supplemented with a "genre module" for Jazz of which several were contemplated but only JazzSupers was produced.
Characters in Jazz are defined by Concept and Ability. Each Ability has a number of "dots" which give a visual indication of how capable the character is with that attribute. Characters will distribute from 25 to 75 "dots" depending on the type of game being run. Characters also have Complications, which describe non-ideal aspects or relationships. Some character build options yield additional "dots", such as writing a Background or taking a substantial Complication. Characters also have Traits which represent areas in which the character has special training or ability. Traits have numeric ratings from 1-7. Characters are assumed to have several Universal Traits which are "things generally known by everyone in a specific culture or time period" (Driving, Native Language, etc.). Characters may also have Talents, which are exceptional abilities (Night Vision, Danger Sense, etc.).
Action resolution depends upon a dice pool of D6. The number of dice in the pool will depend upon the underlying Attribute, Trait, or Talent and its rating.