This is a pretty broad question. In simple terms, a utopia is an ideal or perfect society and a dystopia is the opposite. A "perfect" society in the book is achieved through social conditioning and censorship. In the book, Bradbury doesn't give a clear explanation of why censorship has become so great in this futuristic society. Rather, the author alludes to a variety of causes. Fast cars, loud music, and massive advertisements create an over stimulated society without room for literature, self-reflection, or appreciation of nature. Bradbury gives the reader a brief description of how society slowly lost interest in books, first condensing them, then relying simply on titles, and finally forgetting about them all together. I think Bradbury is commenting on our own world resembling the dystopia in his novel rather than any utopia.