After every shower, Daniel noticed that his bathroom stayed wet for hours. The mirror remained cloudy, towels felt damp, and tiny drops of water covered the walls. He usually left the door closed because he wanted privacy and assumed the room would eventually dry on its own. One morning, however, he noticed a dark patch developing near the ceiling. He wiped it away, cleaned the area, and promised himself he would pay more attention to the moisture.

That evening, after another long shower, Daniel stepped outside and closed the bathroom door as usual. Then he remembered the dark patch and wondered whether closing the door was actually making the problem worse. He opened it, expecting the steam to disappear immediately, but instead noticed humid air drifting into the hallway. He stopped and realized he needed to find a better solution.