The Jedi Lightsaber is a sword-like weapon of a Jedi Knight that was used in the Old Republic and still considered known as the most prominent weapon in the Star Wars universe. Inside a lightsaber is a lighsaber crystal from the Planet Illum. And when turned on, it unleashes any color blades such as green, blue, yellow, or purple.
Lightsabers were used thousands of years before the age of the Republic, in the Great Scourge of Malachor. They were also used in the Battles of Rashfond and the Peacekeeping of Parliock, The proto-saber was an ancient type of prototype lightsaber.
Lightsabers took on a more prominent role in galactic affairs as the Clone Wars came to pass. Jedi, previously peacekeepers, became Jedi Generals of the Grand Army of the Republic, and thus began using their lightsabers more often than they had in their role of peacekeeping.
For the majority of the reign of the Empire, the only lightsaber that was prominently used was that of Darth Vader, and, in its waning years, that of the exiled Obi-Wan Kenobi and Luke Skywalker.
After the Empire was defeated, Luke began training a new generation of Jedi. These, however, were killed during the destruction of his Jedi, once again leading to a time where the only prominent lightsaber user was a darksider, Kylo Ren.
A lightsaber drew power from an appropriately-sized power cell. Parts that would work to make a lightsaber include modulation circuits and an energy gate. Ones that were necessary include a blade emitter shroud, the emitter matrix and some type of activator to turn the weapon on and off. Other parts that could be added include handgrip ridges and a blade length adjuster. Some lightsabers also featured a non-lethal low-power setting used for training. Single-bladed lightsabers usually had a belt ring so they could be hung from a belt hook, or a wheel-shaped attachment that slotted into a matching belt clip on the owner's belt when not in use.
Specially designed lightsabers could even use unstable crystals, such as Kylo Ren's lightsaber, which featured two laterally facing vents designed to divert excess energy away from the cracked crystal and keep the lightsaber stable.
During assembly, it was important to not accidentally invert the emitter matrix; when activated the lightsaber's power grid would backfire. At best this could cause the blade to quickly short out, but if it was left on, the faulty weapon would violently explode, potentially killing those in close proximity.