A "dream" is a series of thoughts, images, and sensations that occur during sleep. Dreams can happen during the rapid eye movement (REM) stage of sleep, when brain activity is high and resembles that of being awake. They can vary in content, ranging from mundane daily experiences to fantastical scenarios. Dreams are believed to serve various functions, including processing emotions and memories. Some researchers suggest that dreaming helps with problem-solving and creativity. While the exact purpose of dreams is still debated, they are a universal human experience that has fascinated people throughout history, including psychologists like Sigmund Freud and Carl Jung.