Gretchen Rubin is an American author and speaker best known for her work on happiness and human behavior. She gained widespread recognition with her bestselling book, The Happiness Project, where she chronicles her year-long experiment to increase her own happiness. Rubin's writing often combines personal anecdotes with research in psychology and philosophy. In addition to The Happiness Project, Rubin has authored several other books, including Better Than Before and The Four Tendencies. She also hosts a popular podcast called Happier with Gretchen Rubin, where she shares practical advice and insights on living a more fulfilling life.