Each of the Empire’s Death Stars was built around a terrifying weapon – a superlaser array capable of destroying a planet. According to legend, the ancient Sith used massive kyber crystals to create superweapons; during the Clone Wars, the Geonosians revived the superlaser design. The Empire constructed the first Death Star in secret for nearly two decades before using it to destroy Alderaan; the second Death Star boasted a more powerful superlaser, with improved targeting sensors and power regulators.
At the heart of every Jedi lightsaber is a kyber crystal found on several planets, most notably the icebound caves of Ilum. This crystal is attuned to the Force, and connected to a Jedi Knight on a deeply personal level. In this way, a lightsaber is an extension of a Jedi's Force awareness. Because Jedi let the Force guide their selection of the crystal, the vibration that the crystal creates in the lightsaber blade helps Jedi center themselves and find balance in the Force. In this way, a Jedi can center his or her attention beyond the distractions of combat. A lightsaber crystal is colorless until first attuned and connected to a Jedi -- at which times it glows either blue or green, or in some rare instances, another shade. From that point on, it retains that hue.
The New Republic’s rise reduced the once-mighty Empire to a rump state hemmed in by strict disarmament treaties and punishing reparations. But in the galaxy’s Unknown Regions, former Imperial officers, nobles and technologists plotted a return to power, building fleets and armies in secret. This movement became the First Order, ruled by Supreme Leader Snoke, and is now ready to reclaim the Imperial legacy.