Lightsabers are laser swords that can cut through almost anything, except other lightsabers. Great for dueling and chopping off arms or the occasional leg.
ConstructionThey may or may not have had crystals in them. Look at the pic!
DesignsLightsabers came in many different designs and configurations. You got your basic lightsaber, of which there are many variations. Then there's curved ones, or double bladed, or even short ones. One of each, please.
Lightsabers came in blue or green for the Jedi, and red for the Sith. One guy had purple. I made myself a silver saber while playing Knights of the Old Republic 2. It was the balls, but unfortunately, silver light sabers do not exists (except for Imperial Knights who likewise do not exist).