A lightsaber is the main close-combat weapon used by both Jedi and Sith. It consists of a beam of energy produced by a small portable hilt generated through a focusing crystal which produces the variations in color seen with different sabers. Changes in the form and function of the blade can be made through adjustments in the field which maintains the length of the energized plasma forming the blade.
The lightsaber is considered a more elegant weapon than a blaster but is often far more dangerous to use, as the weightlessness of the blade takes some getting used to and those who can't completely control it can tend to lose pieces of themselves. Due to the nature of the weapon all of the weight is in the handle and thus makes wielding difficult for those who are not experienced. A minor ability in Force usage is required for skilled use of a lightsaber.
Lightsaber blades are most commonly blue or green for Jedi and red for Sith, due to the relative availability of these colors of crystals. However, orange, yellow, purple, and even pink lightsabers are not unheard of.