A trocar (or trochar) is a medical or veterinary device used in minimally invasive surgery, typically made up of an awl (which may be a metal or plastic with a pointed or tapered tip), a cannula (essentially a rigid hollow tube) and often a seal, and some trocars also include a valve mechanism to allow for insufflation. Trocars are designed for placement through the chest and abdominal walls during thoracoscopic and laparoscopic surgery, and each trocar functions as a portal for the subsequent insertion of other endoscopic instruments such as graspers, scissors, staplers, etc., hence the more commonly used colloquial jargon "ports". Trocars also allow passive evacuation of excess gas or fluid from organs within the body.