Bespin is a major source of tibanna gas, which is refined for production and transport in Cloud City and used in hyperdrive coolant for starships, as well as in the production of blasters. It is home to several million individuals, including humans and Ugnaughts.
The planet is a gas giant that is about 118,000 kilometres (73,000 mi) in diameter. Like most gas giants, it has a solid core that consists of metal followed by layers of metallic gases. Many of the layers of gas are poisonous, and the pressure and temperature are far above what a human could tolerate. But from approximately 150 to 180 km (93 to 110 mi) down from outer space, there is a habitable layer known as the Bespin Life Zone. This layer has an oxygen atmosphere with the temperature and pressure that makes it ideal for human life. It is in this layer that Cloud City is located.Bespin has a number of moons. It has a 12-hour day, and completes an orbit around its star about every 14 earth years (10,220 Bespin days).
By Han Solo's admission, his starship Millennium Falcon barely made it there from the Anoat system without the hyperdrive. Lando Calrissian, the previous owner of the Millennium Falcon, administered Cloud City and provided "well-paying" jobs for the Ugnaughts until the Galactic Empire occupied the system.
During the Galactic Civil War, Darth Vader captured Cloud City (as seen in The Empire Strikes Back) in what became known as the Occupation of Bespin, after blackmailing Calrissian into turning over Han Solo and Princess Leia Organa to him.
The Jedi Knight Streen, an old gas prospector, was discovered on Bespin by Luke Skywalker and recruited to be part of the first class of the Jedi Academy. He had lived in the abandoned Tibannopolis complex as a hermit for years, trying to stay away from the larger galaxy.