What is the use of appendix?

Question

It is the only organ that humans do not khow the use of it?

Answer 1

Medical literature shows that the appendix is not generally credited with significant function. The appendix is rich in infection-fighting lymphoid cells, suggesting that it might play a role in the immune system. Whether the appendix has a function or not, it can be removed without any ill effects or side effects.
The most common explanation is that the appendix is a vestigial structure with no absolute purpose.

Diseases

The most common diseases of the appendix (in humans) are appendicitis and carcinoid tumors.
Appendix cancer accounts for about 1 in 200 of all gastrointestinal malignancies.
An operation to remove the appendix is an appendicectomy (also appendectomy).

Answer 2

We have an appendix because our ancestors ate a much more varied diet than ourselves. It contains enzymes than can breakdown plant matter that ancestors used to eat for example berries. Now it serves no function as we eat less of the same food as back then but evolution has not yet erradicated it.
It is not classed as an organ but an outgrowth of the caecum in the alimentary canal.
Hope that helps :)

Answer 3

In herbivores, the appendix is a place where significant bacterial breakdown of plant matter takes place. In humans, it is a vestigial organ with no function. It's not that we don't know its function, it is that the appendix in humans has no function.