Sexual abuse of a child is generally defined as physical contact or other interaction between a child (under age 17, for example) and an adult when the child is being used for the sexual stimulation or pleasure of the perpetrator or another person. In addition to physical contact, sexual abuse of a child may include (1) the exposure of the genitals of an adult in the presence of a child, (2) the exposure of the genitals of a child, (3) using a child in making pornography, or (4) making a child view sexual acts or pornography.

And in some states multiple instances of sexual contact between an adult and a child may constitute the enhanced criminal offense of continual sexual abuse of a child—which is sometimes a first-degree felony offense.

In Illinois, sexual abuse of a child is a serious criminal offense, encompassing a range of illicit behaviors. Under Illinois law, a child is defined as anyone under the age of 17. The state's statutes criminalize various forms of sexual conduct with a minor, including but not limited to physical sexual contact, indecent exposure, exploitation through pornography, and forcing a child to witness sexual acts or pornography. Illinois law recognizes the severity of these crimes and has provisions for enhanced penalties for repeated abuse, which can be charged under the offense of predatory criminal sexual assault of a child. This is considered a Class X felony, which is the most serious class of felony in Illinois, short of first-degree murder, and carries severe penalties including mandatory minimum prison sentences. The state's legal framework is designed to protect minors from sexual exploitation and to punish offenders accordingly.