(This post is part of my "What Age are you Writing For?" series. You can find the introduction and list of age ranges here.)
Young adult is a very popular genre right now and is often read by readers outside of the intended age range, but the focus of the marketing is 14- to 18-year-olds. Additionally, the main character and the majority of the POV characters should fall within this age group.
The defining features of YA books are the ages of the characters and the teenage focused themes: breaking away from peer pressure, making your own decisions, learning to trust your own judgement, taking responsibility for your own fate, etc. If your book doesn't feature these themes, you may be writing a middle grade or adult novel that happens to have teenage characters.
Word counts in young adult novels average around 70,000, although anywhere from 40,000-90,000 may be acceptable to some publishers. Make sure to check your genre as well as your age range to determine the right word count for your book.
Different publishers may have different rules about what content is appropriate for the YA novel. Some will avoid swearing, leave the physical romances to kissing, and keep the violence levels away from too much gore. Others will allow any swear word, let teenagers have very physical relationships, and include topics like torture, suicide, terrorism, etc. The genre will likely be very important to determining what content is appropriate for your story. A contemporary novel about cancer patients will probably strongly feature mental health and attempt to avoid “cleaning up” the realities of life. A fairytale-retelling might be set in a world at war, but it often will try to polish up some of the grittier or darker parts of life and focus on more happy endings. In general, YA novels aim to be within the rules for a PG-13 rating.
Most young adult novels will have a love interest, even if the relationship doesn’t end up panning out, as teenagers are dealing with the world of romance for the first time and are hormonal enough that life or death stakes don't distract them from an attractive romantic partner.
YA books are often faster paced than adult books and have concise writing styles. They feature more first person and third limited POV styles.
Not the right age range for your book? Check out Middle Grade or New Adult.