Sex offenders are a heterogeneous group. While there is no standardized system for the taxonomy of sex offenders, they are generally classified into various typologies based on their offense characteristics, motivations for offending, and likelihood of recidivism. Typologies are important in that they capture the characteristics of sex offenders, and they can be useful for treatment intervention and risk assessment. However, it should be noted that these typologies do not always coincide with criminal justice classifications of sex offenders. Sex offenders are generally separated into those that commit contact sex offenses and those that commit noncontact sex offenses. Contact sex offenders include child molesters, incest offenders, and rapists. Noncontact sex offenders include exhibitionists, voyeurs, and frotteurs.