It's generally not considered good etiquette to stick a finger up your nose, but feeling inside your nose can be a good way to learn more about how it works.
For example, press your finger toward the middle of the nose and you'll touch what feels like a tough wall, or membrane, made of cartilage. This is called the nasal septum, and it divides the nose cavity into two parts.
Now, in the best of worlds, your nasal septum will be straight and true, dividing the inside of your nose into two equal chambers. However, the world is unfair, and it is not uncommon for a nasal septum to bulge to one side or divide the nose at an angle. A septum that strays from the straight and narrow is called a deviated septum, and it's a not uncommon condition.
Say you venture a finger up your nose and find, low and behold, that you have a deviated septum? First, don't panic. If you've gone this long without suffering any notable sinus problems, nosebleeds, or other nose-related maladies, then your deviated septum is probably nothing to worry about. True, it affects the rate at which air flows through your nostrils, which changes the way you experience smell. However, that's no reason to rush to the emergency room.
You may want to consult a doctor, however, if you suspect that your deviated septum makes it hard for you to breathe through the nose, causes bleeding or headaches, or contributes to excessive snoring. In serious cases there is a routine surgical option to set your septum right.