Sexually transmitted diseases (STDs) — or sexually transmitted infections (STIs) — are generally acquired by sexual contact. The bacteria, viruses or parasites that cause sexually transmitted diseases may pass from person to person in blood, semen, or vaginal and other bodily fluids. It’s crucial to practice safe sex by using condoms, limiting sexual partners, and getting tested regularly if sexually active. Many STDs are treatable with medication, but some may have long-term effects if not diagnosed and managed early. Seeking medical advice and testing if you suspect an STD is essential for proper treatment and to prevent transmission to others.