The lightsaber is a fictional weapon from the Star Wars universe. It is commonly associated with Jedi Knights and Sith Lords. The lightsaber is a unique type of sword-like weapon that stands apart from traditional swords due to its distinctive characteristics:

1. Energy Blade: Unlike conventional swords with physical blades, a lightsaber emits a blade of pure energy (usually depicted as a colored laser) from a hilt. The energy blade is contained within a magnetic field, giving it its distinctive appearance.
2. Plasma Blade: The blade of a lightsaber is often described as being made of plasma, a superheated ionized gas. This plasma is emitted from a crystal (such as a kyber crystal) within the hilt and held in place by the weapon's energy containment field.
3. Length Adjustment: Lightsabers can typically extend or retract their blade length. Users can adjust the blade length according to their preference or combat needs.
4. Unique Colors: Lightsabers are commonly depicted with blades of various colors, which often signify the user's affiliation or role. Blue and green lightsabers are frequently associated with Jedi, while red lightsabers are commonly associated with Sith.
5. Jedi/Sith Weaponry: Lightsabers are closely associated with the Jedi Order and Sith Order, representing their connection to the Force and their skills in combat and control over the mystical energy.

It's important to note that lightsabers are fictional weapons and do not exist in the real world. They are a key element of the Star Wars universe, popularized through movies, books, and other media.