Every fan of Star Wars has seen the many bright colors of lightsabers wielded in battle. Scenes from the First Battle of Geonosis come to mind, where dozens of Jedi can be seen on screen at the same time. The colors are varied and fascinating, and in Star Wars lore, they have significant meaning. Knowing what each blade color represents can help you choose your own lightsaber color and better identify with some of your favorite characters and moments.
Blue was one of the most common lightsaber colors among the Jedi Order. Originally, the color denoted a Jedi Guardian. This was a Jedi who primarily used the Force for physical pursuits. They were often among the most adept in combat.
Green lightsabers were wielded by Jedi Consulars. They were more focused on the mysteries of the force. A Consular might be more likely to be able to use arcane Force powers, and they were more devoted to resisting the dark side.
Yellow sabers were the primary color of the Jedi Sentinels. While they were also adept in combat, they specialized in scholarly pursuits. Sentinels pushed many aspects of discovery through the time of the Jedi Order.
By the time of Episode I, the meaning of lightsaber colors became diluted among the Jedi. Most members of the Order had blue or green lightsabers because the crystals to make them were much more common.
Red typically identifies a user of the dark side of the Force. The red color comes from two sources, and both have been identified in canon. The first is the use of synthetic crystals at the core of the lightsaber. Synthetic crystals are more powerful, and they add a red hue to the blade.
The second source is negative emotions. Sith lords enhance their power through negative emotion. Red is often associated with anger, and this is reflected in Star Wars canon. Anger and other negative emotions fuel the dark side of the Force, and this impacts the color of the lightsaber, and especially the color choice of its wielder.
There is only one black lightsaber. It is called the darksaber, and it was created by the first Mandalorian Jedi. While it might seem that a dark saber is indicative of evil or using the dark side, this is not the case. Instead, the darksaber is strongly associated with the Mandalorians, and anyone wielding it likely had strong ties to the Mandalorians.