Kessel is a tiny planet from the Star Wars
universe. While the planet itself would normally be considered unremarkable - it is a small world which relies on artificial means to so much as hold an atmosphere, it has several unique features which make it of great significance.
Firstly, Kessel is the source of glitterstim spice, by far the most prized of the various spices, both extremely valuable and illegal to distribute. This substance is not only psychotropic, but grants the user temporary telepathy. It is found throughout the planet in veins, and must be mined in complete darkness, since it is extremely sensitive to light (it must only be exposed to light moments before consumption). In the Jedi Academy trilogy of Star Wars books, it is discovered that the glitterstim is in fact secreted by energy consuming spider-like creatures, which lurk the lowest levels of the spice mines, occassionally attacking and sucking the heat energy out of miners and guards. This creature emits no heat, making it impossible to see using the IR goggles used by people working in the mines, making it an especially deadly profession. This, combined with many other mining-related dangers mean that most of the workers are criminals, sent to the planet to work in the mines as punishment.
Kessel's other claim to fame is its proximity to the black hole field known as "The Maw". This made travel near the planet very dangerous, but also served a purpose in smuggling operations, with daring smugglers cutting their journey lengths by skirting dangerously close to the Maw. Han Solo is famous for this, for managing to complete the 18 parsec Kessel Run in only 12 parsecs. Indeed, this was a record for the journey until only shortly before the Battle of Endor.
Also, the Maw hides a major imperial research facility, where such mighty weapons as the Death Star superlaser and the Sun Crusher were designed. This facility is however discovered by the alliance in the Jedi Academy Trilogy and captured, putting an end to its research efforts.