Toilets serve 2 purposes: remove waste & protect air quality. Of all plumbing repairs, this one is by far one the most important repairs that a licensed professional needs to be called upon to perform. Good Plumbing, Inc. in Chicago, IL has proudly served Chicago residents and businesses to ensure the most sanitary environments possible.
It's because "toilet problems" speak to the heart of plumbing: SANITATION. If not repaired properly, a toilet problem will quickly lead to other more serious problems. Even if you simply stop using the facility, that cannot guarantee that a potential health risk is eliminated. A "p-trap" is designed to stop the back-flow of waste gasses from flowing into your home. The water at the bottom acts the barrier between waste gasses and the air your breathe.
From the image you can see how the outlet gasses are literally "trapped" just prior to the elbow. You can also see from the image that a properly working toilet is vital to maintaining a healthy environment.