Yoda was one of the greatest Jedi Masters of all time, serving as Grand Master of the Jedi for hundreds of years, and taking a large role in the training of nearly all of the Jedi in the galaxy during that time.
Yoda was born almost 900 hundred years before the Battle of Yavin. By the time anyone got around to asking him what he was or where he was from, he claimed that he forgot. He encouraged other members of his species, such as Yaddle, to do the same, so nobody would ever learn the true nature of his origin. He thought this was hilarious.
In actuality, he was born on a swamp planet. One day while he was playing his banjo and singing, a bigtime talent agent overheard him and encouraged him to go become famous. Yoda saw an opportunity to bring joy to the galaxy, so he left his homeworld with the hopes of making it big. He joined up with an assortment of woodland creatures and puppets, and was chased by an evil restaurateur who wished to use Yoda as his spokesman. Eventually, Yoda's high force-potential was discovered by a big hollywood producer, and he was send to Coruscant to train as a Jedi.
Despite the fact that he was over 100 years old by the time his trainig began, he was still considered young by his species standards, and was trained with the rest of the younglings.
Yoda learned quickly and rose to the rank of Jedi Knight within a few years. He took a job working for the Jedi Guardian, and was praised for his role in foiling attempt to steal a valuable artifact from a local museum.
Around the age of 150, Yoda was named to the Jedi Council and became the primary teacher of most of the younglings. He enjoyed this work, and took the opportunity to promote his own views of the Force. Since most of the Jedi regarded him as a teacher and elder, he was elevated to the position of Grand Master of the Jedi.
Since the galaxy was mostly peaceful over the next 700 years, Yoda sought to position the Jedi within the Republic as not only powerful defenders, but as wise arbitrators. In order to fulfill this new role, Yoda kept many Jedi busy settling minor disputes and travelling around the galaxy performing odd jobs or making public appearances at dealership openings and local parades.
Re-emergance of the Sith
Despite Yoda's power, he was unaware that the Sith- thought to have been destroyed- had actually just speant about a thousand years hiding. They did not choose to reveal themselves until a pointless trade dispute erupted on Naboo. Jedi master Qui-Gon Jinn had encountered an unidentified Sith Lord on Tatooine while killing time waiting for his ship to be repaired. Many on the Council disputed the notion that there were still Sith hanging around, but Yoda believed Qui-Gon's account, since he had become aware that the dark side had been growing.
After Obi-Wan Kenobi killed the Sith Lord, Yoda focused on finding whatever Sith were still out there.
During this time, he also begrudgingly decided to allow Anakin Skywalker to be trained as a Jedi.
A few years later, Yoda was faced with the reality of full-scale war. Count Dooku's Separatist movement posed a threat to the Republic, and the Emperor sought the power to create an army of the Republic. During a mostly unrelated mission Obi-Wan Kenobi had discovered that an army of clones had been ordered by a rogue Jedi. Yoda took command of this army and led them into battle against the Seperatists' droid army on Geonosis.
Over the course of the Clone Wars, Yoda served as a military leader winnig several key battles for the Republic.
Near the end of the war, during the Battle of Kashyyyk, Yoda's Clones, following Order 66 attempted to kill him, but he sliced through them like a hot knife through butter, and escaped the planet with the help of Chewbacca.
Fall of the Jedi
Returning to the now empty Jedi temple, Yoda learned that The Emperor, secretly a Sith Lord, had orchestrated this entire war for his own benefit, and had turned Darth Vader to the Dark Side. Boy was he embarassed!
Most of the Jedi had been killed, but Yoda and Obi-Wan- both feeling somewhat responsible for ruining the galaxy- attempted to put things right through violence.
Yoda failed to best The Emperor in a pod throwing contest, and, while Obi-Wan defeated Anakin, he let him live for some reason.
Both went into hiding until the whole thing blew over.
Luke wasn't very good at Jedi stuff, and Yoda advised him to stay and train some more, but instead he went off to go fight Darth Vader.
A few years later, Luke came back, and Yoda berated him for being such a punk, then died.
After Luke succeeded by ignoring Yoda's advice, Yoda appeared to him in the form of a hologram that only Luke could see or hear.
Jedi PowersYoda was very powerful. He could sort of see the future, and spent a lot of his time meditating. He was also skilled with a lightsaber and was an excellent teacher.Yoda also had a Force-enhanced sense of humor. He enjoyed few things more than messing with people by pretending to be weaker than he was. He walked with a cane despite the fact that he didn't need it, and played stupid as often as possible. He also liked to go into peoples' offices and start playing with everything on their desks in order to annoy them.
Yoda frequently colaborated with Qui-Gon on practical jokes.