These stories tend to be written and published for, and marketed to adolescents/young adults. According to the Young Adult Library Services Association (YALSA), a young adult is defined as someone who is in the 12-to-18-year-old age range. However, they may be read by adults. These tend to be what is often called coming-of-age stories, and often overlap with Fantasy and Science Fiction. Young Adult stories often feature diverse protagonists who must face challenges and changes.