DragonBall's

DB and DBZ use these crystal sphere to make wishes. If you gather the collection of  7 Dragonballs, a Dragon will appear to grant you your wish. These are used several times throughout the series. On earth, the Dragonballs can be used once a year, granting 1-2 wishes at a time. The dragon at first with Kami-sama could only grant one wish. Dende's Dragon can grant 2 wishes at one time. The earths dragon is named Shenron. Puronga the namekian dragon, can grant 3 wishes at one time. If the creator of the Dragonballs is killed, the Dragonballs disappear. 

After the Dragonballs have been used for whatever wishes it grants, the Dragonballs rise into the air, and fly in all different directions. After they have hit the ground they turn to stone for a year. This is to regenerate their power. After they have regained their power, they are ready to be used once again. 

After the Dragonballs have been used they are scattered across the planet they are used on. In Dragonball GT there are a set of Dragonballs called the Ultimate Dragonballs (Black-Star Dragonballs). When these are used on a planet they scatter across the galaxy. If the ultimate Dragonballs are not collected within one year and brought back to the planet they were used on, that planet will explode.

Rules/restrictions of Earth Dragonballs

1. Must gather all seven Dragonballs.
2. Chant required (Come out, Shenron, and grant my wish!).
3. Only 2 wishes per summoning of Shenron.
4. After the wishes are made, Shenron will disappear, the Dragonballs
will turn to stone and scatter themselves; they will remain stone
for 1 year (6 months if you choose to only have one wish)
5. The Shenron cannot grant any wishes that are beyond the powers of
the creator of the Dragonballs.
6. You can revive anyone or any group of people who fit a certain
criteria, if they did not die of natural causes.
7. If a person has been revived by Shenron before, the person cannot
be revived again.
8.You can't wish for more wishes

Rules/restrictions of Namek Dragonballs

1. Must gather all seven Dragon Balls.
2. Chant required in the Namek language.
3. Wishes must be said in the Namek language.
4. Only three wishes per summoning of Puronga.
5. After the wishes are made, Puronga will disappear, the Dragonballs
will turn to stone and scatter themselves; they will remain stone
for 130 days.
6. Puronga cannot grant any wishes that are beyond the powers of the
creator of the Dragonballs.
7. You can revive anyone multiple times, as long as he/she did not
die of natural causes.
8. You can only revive one person per wish.
9.You can't wish for more wishes