In human anatomy, the vermiform appendix (or just appendix) is a blind ended tube connected to the caecum. It develops embryologically from the caecum. In adults, the appendix averages 10cm in length but can range from 2-20cm. While the base of the appendix is at a fairly constant location, the location of the tip of the appendix can vary from being retrocaecal to being in the pelvis to being extraperitoneal.

While most believe the appendix is a useless and purely vestigial organ; others suggest it may have a function in the lymphatic system.

An operation to remove the appendix is an appendectomy.

The most common diseases of the appendix (in humans) are:

see also digestive system