It deals with a fantastic land called Katroo, where the Birthday Bird throws the reader an amazing party on their special day. It consists of a running description of a fantastical celebration, narrated in the second person, of the reader's birthday, from dawn to late night.
The celebration includes fantastical and colorful gifts, foods and a whirl of activities all arranged by the Birthday Bird for the reader's birthday. It focuses on the reader's self-actualization and concludes with the happy and exhausted reader falling blissfully asleep.
A popular Seuss paragraph in this book reads: "Today you are you, that is truer than true. There is no one alive who is youer than you".[2]