Yoda is a much respected Jedi Master and a master of the Force.
He is the leader of the Jedi council, the group which oversees all of the Jedi.
The Jedi act as peacekeepers for the Galactic Republic and their powers, although used for good, are often feared.
Using the Force, Master Yoda is able to look forward in time and into people's minds. Like all Jedi, he wields a lightsabre and can command the weak-minded.
When the Republic turned into the Empire, Yoda and his fellow Jedi, Obi-Wan Kenobi, were forced into hiding.
Yoda spent his final years living on the swamp planet of Dagobah, where shortly before he died, he took on his last apprentice, Luke Skywalker, sent to him by the ghost of Obi-wan.
Yoda trained Luke as he had trained many Jedi before him and eventually told Luke the truth about his father.