For most of you, the only real experience you might have with your appendix is likely a bad one – namely, that something went wrong and it had to be removed. You probably even received a nice scar as a souvenir of the event. But what exactly is the appendix and what does it do?
The appendix is a tube-shaped sac opening into the large intestine. It exists in humans as well as a small number of other mammals, including the koala and apes. In medical terms, it's referred to as ‘vermiform appendix' for its thin, worm-like shape. For years, the appendix was dismissed as a lingering souvenir of our evolutionary past.
Many scientists—including Charles Darwin—believed this small pouch protruding from the large intestine was a vestigial organ that once helped humans to digest tree bark. Since tree bark is no longer included in the daily diet of the average human, it was presumed that the appendix no longer served a function. However, more recent research from the Duke University Medical Center suggests otherwise.
Surprising Functions of the Appendix
Far from being useless, the appendix may produce and protect beneficial germs in the digestive system. According to researchers, the human digestive system is full of bacteria necessary to digest food.  Under attack from diseases such as cholera or dysentery, sometimes these important kinds of bacteria are purged or killed off. In such situations, the appendix can act as a reserve for good bacteria. After the immune system beats off the disease, the bacteria emerge and re-colonize the gut.
While the appendix may play a helpful role in the human body, it still carries the potential for harm that we alluded to above. Appendicitis is a common and serious appendix-related disease where the appendix becomes inflamed and can rupture, resulting in detrimental, often fatal consequences. Studies from the Centers for Disease Control and Prevention found that around 300 to 400 Americans die from appendicitis every year. 
Even though the appendix may serve a useful purpose, it's important to get the appendix removed in the event of appendicitis and other appendix-related diseases. Removal of the appendix is a commonplace procedure without any apparent negative effects, and neglecting to have it removed once it becomes inflamed could be very harmful.
-Dr. Edward F. Group III, DC, ND, DACBN, DCBCN, DABFM
- Duke Medicine News and Communications. Appendix Isn't Useless at All: It's a Safe House for Bacteria. Duke Medicine.
- NBC News. Scientists may have found appendix's purpose. NBC Health News.
Source: What Does the Appendix Do?