The exact cause of appendicitis is still not clear. Appendicitis is the result of a blockage in the lining of the appendix. This blockage is due to the fecal matters getting stuck in the appendix which then leads to infection.
Another reason can be the parts of indigestible food getting stuck in the appendix while they pass from small intestine to large intestine. Either way, once infected, the bacteria spreads and causes inflammation in the appendix.
Sometimes the appendix may burst as the inflammation increases. This is the reason why doctors around the world suggest to get diagnosed and seek medical attention immediately if you have a concern that you have appendicitis. If the appendix bursts, the bacteria will spread throughout the stomach and the abdomen.