The Dragon Ball series has to be one of the most popular and longest running anime series. The series started with a girl named Bulma in search of the seven magical Dragon Balls. It is told that when all seven dragon balls are collected, it will summon the Dragon can grant one wish to the person who collected all seven balls. After that wish is fulfilled the Dragon will disappear and the dragon balls will separate and spread out all over the world, until someone else finds them. Along her travels Bulma runs into Gokou, who is a young martial artist that seems to have super powers. Gokou and Bulma begin a journey to find the seven dragon balls and along the way they run into wide array of characters, who will either become friend or enemies.
In Dragon Ball Z the story focuses more on Gokou and his heritage as a Saiyajin. Gokou is now grown up and is married to ChiChi. They have a son named Gohan who's half Saiyajin and is quite strong like his father. The Saiyan's are a super powered race who are bent on destroying and conquering worlds. Gokou was originally sent to Earth to destroy all life on the planet but as a child his brain got scrambled and he became kind and good-natured. The series continues with Gokou and friends encountering more and more powerful enemies, as they themselves grow in strength.
Since the story about the seven dragon balls seemed to have been a minor part in Dragon Ball Z, it has been revisited in Dragon Ball GT. In Dragon Ball GT, Gokou has been accidentally turned back into a child. It turns out that the Red Dragon who granted the wish which turned Gokou into a child, wasn't the normal Green Dragon. The dragon balls spread out all over the universe and if all seven balls were not placed together within one year the planet where the wish was made will be destroyed. So in order to turn Gokou back into his adult form and to save Earth, Gokou, Trunks and Pan journey into outer space in search of the Dragon Balls.