The Happiness Project by Gretchen Rubin is a revised trade paperback published by HarperCollins in 2015. This self-help book focuses on personal growth and happiness, exploring various aspects of personal development in a general sense. With 336 pages, the book delves into the author's year-long project to identify the keys to long-term happiness and provides practical advice for achieving a more fulfilling life. Written in English, this bestseller offers insights and strategies for those looking to enhance their overall well-being and happiness.