Pollyanna is a 1913 novel by American author Eleanor H. Porter, considered a classic of children's literature. The book's success led to Porter soon writing a sequel, Pollyanna Grows Up (1915). Eleven more Pollyanna sequels, known as "Glad Books", were later published, most of them written by Elizabeth Borton or Harriet Lummis Smith. Further sequels followed, including Pollyanna Plays the Game by Colleen L. Reece, published in 1997. Due to the book's fame, "Pollyanna" has become a byword for someone who – like the title character – has an unfailingly optimistic outlook; a subconscious bias towards the positive is often described as the Pollyanna principle. Despite the current common use of the term to mean 'excessively cheerful', Pollyanna and her father played the glad game as a method of coping with the real difficulties and sorrows that, along with luck and joy, shape every life.