The Everworld Series is a young adult fantasy book series written by K.A. Applegate. It follows a group of teenagers who are transported to a magical realm called Everworld, where they encounter various mythological creatures and gods from different cultures. The series explores themes of friendship, adventure, and the struggle between good and evil. The main characters, including Jared, April, David, and Christopher, navigate the challenges of this new world while trying to find a way back home. Each book delves into different aspects of Everworld, blending elements of mythology with the characters' personal growth and relationships.