The "Railway Series" is a collection of children's books created by Rev. W. Awdry and later continued by his son, Christopher Awdry. The series features anthropomorphized trains and their adventures on the fictional Island of Sodor. The first book, "The Three Railway Engines," was published in 1945, introducing beloved characters like Thomas the Tank Engine. The stories emphasize themes of friendship, teamwork, and problem-solving. Over the years, the series has expanded to include over 40 books, along with adaptations into television shows, merchandise, and films, making it a significant part of children's literature and popular culture.