If you've never read the book or seen the movie, and since I'm not good with words, I found this review (below the following image) and had to copy and paste it as I couldn't have said it any better. Oh to be young and carefree again!
My mother first bought this book for my oldest son. It has endured as a beloved favorite to all three of my boys. I think that children can really identify with Max and his thoughts. When he is sent to his room for misbehavior, his imagination helps him to run away to where the wild things are and collect his thoughts. I believe that the author must remember what its like to be a child and feel like no one understands, and not quite understanding yourself. Ruling the wild things helps Max understand that he just wants to feel loved, and helps parents to keep in mind that such outbursts from children are generally cries for attention--for someone to love them best of all. Mr. Sendak understands children! When you read this book it will transport you back to your own childhood and you will remember that lost feeling of being a child. Bravo, Maurice! You are my hero! - Lisa Forrest, Sunman, IN
Here are some pictures of Max and his BFF, Carrol: