In Dragonball Z, there are many storylines known as Sagas. They are:
The Radditz Saga
In the Radditz Saga, Goku's evil brother Radditz arrives on Earth to tell Goku of his true Saiyan heritage. When Goku is told that the real reason he came to earth was to scout it for a possible takeover, he is astounded when Radditz asks him to continue on with the mission. When Goku refuses, Radditz kidnaps Goku's four year old son Gohan and tells Goku that the only way to get him back is if Goku kills 100 people. Goku knows that he will never do this, so the only other option is to fight Radditz. Piccolo, Goku's onetime enemy, knows that together they can beat Radditz. So, they team up and fight Radditz. During the fight, Goku is injured so an enraged Gohan breaks out of the Saiyan Pod that Radditz was keeping him in and headbutts Radditz , who is very powerful, in the stomach. This distracts Radditz long enough for Piccolo to fire his special attack he had learnt to use on Goku, the Makkankosoppon, or Special Beam Cannon. But, Radditz dodges it and Piccolo tells Goku that he can only use it once more. Goku grabs Radditz and tells Piccolo to fire it. Piccolo does, and the attack goes through Goku and Radditz, killing them both. As Radditz is dying, Piccolo tells him that they will just wish Goku back with the Dragonballs. Unfortunately, two other Saiyans are listening to Piccolo's tale of free wishes from the Dragonballs...
The Saiyan Saga
The two Saiyans that heard Piccolo's conversation have came to Earth. Goku, having died, was training in heaven with King Kai. Yamcha, Tien, Piccolo, Gohan and Kuririn are all training in preparation for the Saiyans. When the Saiyans arrive, there are two: Nappa, a muscly bald headed fighter, and Vegeta, a smaller but powerful fighter. In the ensuing battle with Nappa, Yamcha is killed by a special plant, which grew into a monster, and Chaou-szu self destructs in an effort to kill Nappa. Tien, in anger at his friends death, tries to attack Nappa, and is too killed. Menawhile, Goku, who is watching the battle, was wished back to life using the Dragonballs, and came hurrying to help Gohan and Kuririn, who were about to be attacked by Nappa. During his time with King Kai he had learnt two new techniques, Kaioken, which multiplies the fighters speed, agility, and fighting power, and the Genki Dama, a huge energy attack that harnesses its power from all living things. He arrived in time to defeat Nappa easily with his new powers and strength. Vegeta, fed up with Nappa, finishes him off after Goku left him to recover. Goku is then challenged by Vegeta, their first battle of many...during the fight, Goku seems to be winning using his Kaioken attack, then Vegeta uses his Galet Gun and things turn around slightly...Vegeta then goes Oozaru and beats up Goku, but luckily, Yajirobe, who had been hiding, comes out and cuts off his tail with his sword, and he returns to normal. Then Gohan, using the moon, becomes an Oozaru and fights Vegeta. Vegeta cuts off his tail and then Gohan, still in Oozaru mode, falls on him. Vegeta, knowing he is beat, staggers off to his Saiyan Pod. Kuririn, angry at him, wants to go after him with the sword and finish him, but Goku will not let him. So, they all once again head off to train some more and the next saga arrives...
The Frieza Saga
Bulma, Gohan and Kuririn hear about how Piccolo is an alien from the planet Namek. They wonder if Namek has dragonballs as well, so they decide to go on a mission to the planet. They arrive and are greeted with a group of Namekians. They discover that there are Namek Dragonballs and they set out to find them. Unfortunately, they aren't the only ones who want to find them. Frieza, the person who destroyed Goku's home planet and his father, is also looking for the dragonballs, so he can wish for eternal life. And guess what, Vegeta is there too, looking for the dragonballs. In the end, Frieza and Vegeta, first together and then as rivals, go after the dragonballs, destroy many Namekians and their villages in search of the seven orange spheres. Zarbon, one of Frieza's men, has a fight with Vegeta, and loses. Meanwhile, Gohan and Kuririn are continuing their search for the dragonballs. Goku, busy training in space was surprised to hear from King Kai that Bulma, Kuririn and Gohan were in great danger from Frieza, who was immensely powerful. Against King Kai's warnings, Goku goes ahead and tries to help them. Frieza has by that time got six of the dragonballs, but Vegeta, who is recovering inside Frieza's ship, escapes and kills the guard, and steals the dragonballs. This makes Frieza very angry, so he sends Zarbon out to retrieve then. When Zarbon and Vegeta fight again, although Zarbon has used his monster transformation skills, Vegeta kills him. Then he attacks Gohan in order to get his Dragonball. Soon, the inevitable happens: Gohan, Kuririn, and Vegeta have to team up in order to defeat Frieza. While Vegeta is sleeping Gohan and Kuririn summon the Namek Dragon and wish back Piccolo thanks to a little Namekian named Dende who they rescued. Piccolo, who has just fused with injured Namekian Nail, comes to help in the fight but Vegeta is furious that they wasted his wishes. Frieza then makes his move and the fights between Vegeta, Kuririn, Gohan and Piccolo occur. Vegeta is killed just when Goku arrives. Goku then fights Frieza, who has by that time transformed into his fourth form. In the final fight, after a long and drawn out battle, Frieza kills Goku's best friend Kuririn, and Goku is pushed over the edge and becomes a Super Saiyan. (See Saiyans) He finally defeats Frieza and emerges the winner. However, in the battle Frieza launched a death ball at the planet, damaging it to the core. By now, Namek is about to blow. Goku manages to get off the planet just in time. Meanwhile, while the fight was going on, the others have used their remaining wishes to summon the dragon and wish that everyone killed by Frieza is brought back to life, including Vegeta. Then, they are all wished to Earth, out of the way of the fighting. This was how Goku wanted it. Goku escapes off the planet and has a few adventures before returning to Earth...
Garlic Jr. / Trunks Saga
These are two 'sagas' which follow after the Frieza one. In the Garlic Jr. one (which I'm not going to say much about as it is crap), basically, an evil Namekian with the power to make people Evil has escaped from the Dead Zone (see the movie for more details) and wants to get revenge...or something...anyway, Gohan and Piccolo and Kuririn all destroy him and that's all anyone needs (or wants) to know. In the Trunks 'saga', basically, Frieza is back (this crops up again and again in DBZ and DBGT. This is, because no-one ever takes dying seriously in DBZ...there's always a way out...) and he is built up as a robot - Friezabot. He is back with his father, King Cold, and his hired goons. Anyway, a mysterious young Super Saiyan from the future arrives just as the good 'ol Z fighters (minus Goku) are beginning to crap themselves. He kills Frieza and then King Cold with his seemingly magical sword, Excalibur. He tells no-one but Goku who he is (Goku arrives soon after as predicted by the youth) It turns out that his name is Trunks, and he is Vegeta and Bulma's son from the future. He came back in a time machine to tell Goku and the Z fighters of a group of menacing Androids that are terrorising his future and soon the Z fighters, who in Trunks' time, are all dead. He warns Goku that in the future, he has died of Heart Disease, so he gives Goku a heart medicine that Bulma had developed for him. Then, Trunks leaves, back to his time, and no-one knows who he is except Goku…(and Piccolo who had overheard the whole conversation with his big ears)
The Android Saga
After Goku and Trunks' conversation about the androids coming to kill them all, (except for Gohan) the Z fighters decide to train in preparation for the arrival of the Androids in 3 years. I won't bore you with the details, but basically, Vegeta starts to train at 400+ times normal gravity, in an attempt to reach the stage of Super Saiyan. The rest of them basically train and the good old 'Three Years later' apears after three episodes. So, the Androids,(#19 and #20) arrive, and Yamcha (lucky feller) is the one to find them. After having a hole put through his chest by #20, he is found by the others and taken off to be healed by Kuririn. Goku, Tien, and Piccolo are then facing off with the Androids. Goku says that they should go to a more out of the way place to fight, so they do. Android #20 then reveals that his creator, Dr Gero, has been observing Goku and the other fighters since back in Dragonball., noting and copying their training and moves. Piccolo then asks if they were watchinbg when Goku was fighting on Namek with Frieza. Android #20 tells him that they had enough data by that time and didn't watch. Goku then surprises the Androids by going Super Saiyan in front of them, a stage they had never seen before. So, the first fight begins. Goku vs Android #19, the fat one with the dodgy voice. As they fight, Goku, who is winning, begins to slow down and have a hard time. This is his heart disesase that Trunks warned him about kicking in. Just as it appears that Goku is about to lose, help comes in the form of...shock horror...Vegeta! Vegeta lands there, and to everyones surprise, he goes Super Saiyan! He then proceeds to beat the crap out of Android #19, and after he learns that the Androids absorb peoples energy through their arms, he rips off Android #19's and blows him to pieces with a mighty blast. Android #20, realising that Vegeta is now stronger than they thought, legs it, and heads for the hills. Vegeta, in true Saiyan Prince style, follows him and searches for him. Anyway, the Z fighters learn from Bulma is actually the craetor, Dr Gero, remade as an android, reveals that he has a secret lab, where he stores more of his evil creations. So it is a race between the Z fighters and Dr Gero to get there first. Gero wins and release Androids #17 and #18, his most powerful creations. They then proceed to release Android #16, an unfinished Android made only to kill Goku (This is all about revenge for what Goku did to the Red Ribbon Army back in Dragonball) and then Android #17 kicks off his creators head.
Cell Saga
:The cell saga is when cell finally is born into his first form he then go on a long quest to find #18 and 17 but he has a lot in his way before he can asorb them his first comes along a line where he asorbs a bunch of humans. which his power level rises from 6,000,000 to 8,000,000 after he has stronger power he goes off in a fight against the andriods but goku vegeta and trunks are in his way so it starts off when andriod 16 challenges him 16 was a good fight but 16 was a litte too slow and cell gets to #17 and asorbs her now 16 gets manually kicked to pieces 18 tries to fight him but stands no chance of winning she then goes to 16 and forces him to fly her out but they are too slow and 16 gets beat again but while 16 and cell were fighting 16 tells 17 to escape so she does but with worry for #16 then after vegeta and trunks get done from training vegeta challenges cell ,cell is easily beat down but vegeta lets him asorb18 and cell goes to 3rd form and then vegeta is down so trunks is all who is left since goku and gohan are training so while trunks and cell are fighting trunks tells krillin to give vegeta a senzu bean and get him out of here trunks go into super saiyan...after a while of fighting goku and gohan are finally done now the 10 day wait to the cell games is here..... !!!1!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!MAJOR SPOILER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The winnner of the tourna ment is gohan with a super kamehameha
More Sagas soon!!