Now that we know Anakin was once a Jedi, you might be wondering why he turned to the dark side.
Thankfully, that's explained in the prequel trilogy, starting with "Star Wars: Episode I — The Phantom Menace," which introduces us to a young Obi-Wan, who is the padawan of Jedi Master Qui-Gon Jinn. During the film, the two find themselves on Tatooine, where they meet Anakin as a young boy, and after sensing that he's strong with the Force, Qui-Gon promises to train him to become a Jedi. However, after he dies, Obi-Wan trains Anakin instead.
Unlike the original Star Wars films, during which the Jedi are nearly extinct, the prequel trilogy shows the Jedi in full force. Through "The Phantom Menace," we learn about Anakin and his mother's lives as slaves, as well as how he's able to become free by joining the Jedi Order. We also see firsthand how he meets Obi-Wan and his eventual wife Padmé Amidala.