IRC+10216, also known by its variable star name CW Leonis, is a red giant star on the asymptotic giant branch with a carbon-rich atmospheric composition, i.e., the atmospheric abundance of carbon exceeds that of oxygen. It is probably the most nearby object of its kind, and it loses substantial amounts of matter from its surface. This stellar wind creates a dense circumstellar envelope which is rich in molecules and carbon dust. More than 80 different circumstellar molecular species have been detected, the majority being long, unsaturated, carbon chains of different types (incl. anions) and many of them being unique to the circumstellar medium.