Wookiees are a species in the Star Wars Galaxy, whose homeworld is on the planet Kashyyyk. Chewbacca from the Star Wars film trilogy is a wookie, and Kashyyyk can be seen in Star Wars: Episode III, Revenge of the Sith. Wookies are taller than normal humans, and covered in dark hair all over their bodies. Wookiees can easily understand most languages, such as Basic (English), but their voices cannot emulate the noises required to speak these other languages, so Wookiees only ever speak in their native language, characterized by harsh, guttural growls and yelps. Wookiees are highly intelligent, and possess a very strong grasp on technology, including starship and hyperspace capability. The average Wookiee lifespan is roughly six hundred years, about seven times the average lifespan of a human. Wookiees are famously short-tempered, giving rise to the famous phrase: "Let the Wookiee win".
The Wookiees have a unique and multi-layered culture that most outsiders do no understand. The most famous Wookiee tradition is the Life-Debt, where a Wookiee whose life has been saved by another person, Wookie or not, will swear themselves to follow that person for the rest of their life. Chewbacca's Life-debt to Han Solo is a prime example of this concept, as is the Life-debt Zaalbar swears in Knights of the Old Republic. Life-debts are a matter of personal honor among Wookiees, and to turn one down is an intense personal insult to the Wookiee.
It is also known that although Wookiees have incredibly vicious and dangerous claws, using them against another Wookiee is strictly forbidden, and doing so is an extreme shame to whoever attacked. Wookiees who committed this heinous crime were labeled "madclaws" and usually sent into exile. Wookiees view use of their claws as a weapon against each other as feral and shameful behavior, as they prided themselves on being an advanced civilzation.