What do the audience categories in Libby mean?

Libby's content controls are based on titles' audience categories. There are four audience categories in Libby:

• Juvenile: Titles intended for readers ages 0-12.
• Young adult: Titles written for readers ages 13-18.
• General content: Titles written for adult readers or a general audience. This is the audience category for most titles.
• Mature content: Titles intended only for mature audiences due to the nature of their content.