Sexting among youths has become a necessary topic of interest in research because of the negative consequences that this activity could create, especially when content is shared with others. Indeed, this loss of control could lead to humiliation, (cyber)bullying, or harassment. The development of new technologies, press coverage, and increase of prevalence rates could also explain the growth of interest in sexting. However, its definition is still a gray area. This review examines the different definitions of sexting used in the literature and its correlates. Several elements of the definition of sexting were assessed: actions (sending, receiving, and forwarding); media types (text, images, and videos); sexual characteristics; and transmission modes. Nine databases were searched for studies on sexting among youths up to 18 years of age. Eighteen studies published between 2012 and 2015 were included. Prevalence rates of sexting ranged between .9% and 60% partly depending on the definition. Most studies assessed sending, but when sending and receiving were measured, prevalence rates were higher for receiving. Some articles found associations with age, gender, race, sexual behavior, romantic relationships, risky behaviors, online activity, psychological difficulties, and social pressure. Finding a consensus regarding the definition is essential to assess accurately the activity and adapt prevention. Adolescents' interpretations of the activity are important as sexting could be used as a sexual behavior between two consenting persons. Prevention strategies should focus on sexting that goes wrong when it is forwarded to a third party and when it occurs in a context of pressure or harassment.