There are basically 7 Dragon Balls which when brought together, would bring out a Dragon which would grant wishes. However, there are different types of Dragon Balls scattered all around the universe. Here are some info on what Dragon Balls and their Dragons are all about. Dragon Balls are introduced by the Nameks. They are the one who specialise in the creation of Dragon Balls.

The Earth's Dragon Balls are mostly scattered all around Planet Earth. Earth's Dragon Ball could only grant 1 wish each time the Dragon is called upon. It'll take 1 year for the Dragon Balls to regenerate from the stone form. Earth's Dragon Ball can grant almost every wish except for destroying enemies which are far more stronger than it. It can also increase people's energy level, for example, becoming younger or stronger than before. Earth's Dragon could only revive 1 person's live once.

The Namek Dragon Balls are scattered all around Planet Namek. Once the Dragon is called upon, one can grant 3 wishes at once. However, the Dragon need to be summoned using Namek language. It'll take 1 Namek year for this Dragon Ball to regenerate from stone form. The only wish that cannot be granted by this Dragon Ball is destroying objects that are much more stronger than it. However, the same person could be revived more than once.

Another Dragon Ball which was created by earth's Namekians. It was created before Piccolo and Kami split. Black Star Dragon Balls could grant up to 3 wishes. It is one of the most powerful Dragon Balls. Wishes are not allowed to be taken back or reversed. These Dragon Balls are also hard to find because they are spreaded across the universe. These balls are instantly regenerated, but if they are not found in between a year, planet earth would be destroyed by monsters living inside the Dragon Ball.