Chlamydia is a common sexually transmitted disease (STD) caused by the bacteria Chlamydia trachomatis. It can cause infection in both men and women and can lead to serious health issues if left untreated. Chlamydia can cause cervicitis, urethritis, and proctitis, and in women, it can lead to permanent damage to the reproductive system, potentially causing infertility and ectopic pregnancy. The infection is usually spread through vaginal, anal, or oral sex with an infected individual, and it can be transmitted even if there is no penetration, orgasm, or ejaculation. Due to its often asymptomatic nature, many people may not realize they are infected, making regular testing and safe sexual practices important for prevention and early treatment.