There is some debate about what makes a book a "young adult book". I tend to define the genre more broadly as books that are written for, marketed to, and/or read by young adults ages 12-21.
The young adult book genre is unique in that it is fairly new. S.E. Hinton's The Outsiders, published in 1967, is often cited as the first young adult book. Since then, the genre has exploded in popularity and number of titles. Though some still view young adult books as a lesser genre, most readers have come to appreciate young adult literature for its innovation, literary merit, and ability to speak to its audience. In fact, I believe that some of the very best writing today is being produced within the young adult genre.
Young adult books are worth reading at any stage of life because you're never too old for a good young adult book. Or any good book for that matter.
