Comprehensive sex education in the context of "Abstinence-only sex education"

A sexually transmitted infection (STI), also referred to as a sexually transmitted disease (STD) and the older term venereal disease (VD), is an infection that is spread by sexual activity, especially vaginal intercourse, anal sex, oral sex, or sometimes manual sex. STIs often do not initially cause symptoms, which results in a risk of transmitting them to others. The term sexually transmitted infection is generally preferred over sexually transmitted disease or venereal disease, as it includes cases with no symptomatic disease. Symptoms and signs of STIs may include vaginal discharge, penile discharge, ulcers on or around the genitals, and pelvic pain. Some STIs can cause infertility.

Bacterial STIs include chlamydia, gonorrhea, and syphilis. Viral STIs include genital warts, genital herpes, and HIV/AIDS. Parasitic STIs include trichomoniasis. Most STIs are treatable and curable; of the most common infections, syphilis, gonorrhea, chlamydia, and trichomoniasis are curable, while HIV/AIDS and genital herpes are not curable. Some vaccinations may decrease the risk of certain infections including hepatitis B and a few types of HPV. Safe sex practices such as the use of condoms, having smaller number of sexual partners, and being in a relationship in which each person only has sex with the other also decreases STIs risk. Comprehensive sex education may also be useful.

Adolescent sexuality is a stage of human development in which adolescents experience and explore sexual feelings. Interest in sexuality intensifies during the onset of puberty, and sexuality is often a vital aspect of teenagers' lives. Sexual interest may be expressed in a number of ways, such as flirting, kissing, masturbation, or having sex with a partner. Sexual interest among adolescents, as among adults, can vary greatly, and is influenced by cultural norms and mores, sex education, as well as comprehensive sexuality education provided, sexual orientation, and social controls such as age-of-consent laws.

Sexual activity in general is associated with various risks and this is heightened by the unfamiliar excitement of sexual arousal, the attention connected to being sexually attractive, and the new level of physical intimacy and psychological vulnerability created by sexual encounters. The risks of sexual intercourse include unwanted pregnancy and contracting a sexually transmitted infection such as HIV/AIDS, which can be reduced with availability and use of a condom or adopting other safe sex practices. Contraceptives specifically reduce the chance of teenage pregnancy.