Transfer cases are a little more complicated than your typical drivetrain component, so let's start with a quick overview. The transfer case is what allows you to change gears while driving in Massapequa, NY.
It's two different transmissions that are connected by a chain or belt, and it allows you to swap between high and low range and neutral. This makes it possible for an all-wheel-drive vehicle to handle both highway cruising and serious off-roading without any problems.
The transfer case is an important part of your vehicle, but most people don't need to know much about it unless something goes wrong. You can usually ignore it until something breaks or starts making noise, at which point it becomes very important indeed.
If your transfer case is making strange noises or not working properly, you should take it to a professional who can diagnose the problem and repair or replace anything that needs fixing.