Do you know how much water you can find in an average load of laundry? Of course, it depends on the type of material and how big the load is, but usually there will be about a gallon. When you run those clothes in the dryer, that water is turned into steam, but where does it go? The answer is that it goes out your dryer exhaust through the attached hose. Unfortunately, not everyone has this set up properly.
It is very important that your moist air gets funneled to the outside, and 3 feet away from any doors and windows, as well. This is important since that air could cause moisture related problems in your home if it ends up in there. To ensure proper exhaust from your dryer, the hose leading out needs to be as straight as possible. You should occasionally check for blockages that could build up in the hose due to lint, since this could be a serious problem, even causing a fire.