Dreams have captivated human imagination throughout the time. However, in the year 1900, dreams also gained an important place in psychotherapy when Sigmund Freud proposed that dreams were the royal road to the unconscious. The following book presents an overview of the history of dreams and discusses the shift from the use of latent content to that of the manifest content during dream analysis. Additionally, various methods of dream interpretation, the functions of dreams, differing schools of thought on the utility of dreams, typical dreams, and the biological challenge to dream theory are discussed. From antiquity, the universal phenomena of dreaming has captivated human imagination, confused human logic, and controlled human endeavors. Dreams have been regarded as very important, as messages from the gods, predictive of the future, expiatory of guilt, and the voice of conscience. Shamans, seers, and saints have used dreams to discern the source of sickness or to set the course of nations. Poets, philosophers, and playwrights have sought to plumb the depths of dreams in order to lure audience or readers into the world of fantasy, to play the strings of the emotions, and to recall the unthinkable. Cognitive, information processing, and neuroscientists find in dreams brain activity that can help understand REM, memory consolidation, and the "unconscious" state.