Sexually transmitted infections (STIs) are primarily caused by bacteria, viruses, and parasites. The most common modes of transmission include unprotected sexual contact, having multiple sexual partners, and sharing needles. Understanding these main causes is crucial for the prevention and effective management of STIs. By staying informed and practicing safe sex, such as using condoms and limiting the number of sexual partners, individuals can significantly reduce their risk of contracting infections. Regular testing and avoiding the sharing of needles are also important preventive measures. Stay informed, practice safe sex, and take proactive steps to protect your sexual health.