The Jedi Order was founded in 25,783 BBY. They were the guardians of Light and peacekeepers across the galaxy.
For many thousands of years they fought against and uncovered plots by the Sith, who used the dark side of the Force.
The Jedi Order consisted of all races, both human and non-human who were strong in the light side of the Force. Yoda, Obi-Wan Kenobi, and Luke Skywalker were among the most well-known Jedi Knights.
The Clone Wars almost completely destroyed the Jedi as there had been a one-thousand year old plan by the Sith to bring about their downfall.
The Sith's greatest triumph aside from battles was turning former Jedi Anakin Skywalker to the dark side, where he became Darth Vader - the Emperor's right hand.
Vader sought to turn his son, Luke Skywalker to the dark side, but in the final event he found enough humanity left inside to save him instead and kill the Emperor.