"Understanding Media" is a book by Marshall McLuhan that explores how different forms of media influence human perception and society. McLuhan famously coined the phrase "the medium is the message," suggesting that the way information is delivered affects how it is received and understood, often more than the content itself. The book discusses various media, including print, television, and radio, and their impact on culture and communication. McLuhan emphasizes that each medium shapes our experiences and interactions, leading to profound changes in social structures and individual behavior. Understanding these effects is crucial for navigating the modern media landscape.