A sex offense is a form of human sexual behavior that is harmful to at least one individual involved in certain sex acts. Such an offense is so destructive to society that it is regarded as a criminal act. Some sex crimes involve violence while others do not. There are several adult sex offenses that require the perpetrator to register as a sex offender in Texas. Some include sexual assault, sexual performance by a child, sexual assault of a child, indecency by contact or exposure, solicitation, child pornography, etc. (See Chapter 21 of the Texas State Penal Code for a more complete list.)