Agnes was young and beautiful. She was also, more importantly, a Roman Christian during Diocletian's persecution against Jesus' followers. When the girl refused the advances of numerous suitors, charges of being Christian were brought against her. When at her trial she refused to offer worship of pagan gods, the judge threatened her with various forms of torture. Agnes remained true to her faith.
This twelve or thirteen year old girl was then sent to a brothel to be used by any men who wanted her. According to tradition no man could violate her because of her pure spirit. The girl was then beheaded (or burned, or executed by sword, depending on which version of the story). She is buried at the church of Sant'Agnese on the Piazza Navona in Rome.
Since the fourth century, Agnes has been venerated for her chastity and faithfulness. Her emblem is the lamb, symbol of innocence and purity (and also similar to her name in Latin).
Agnes is the patron saint of young girls.
Image is detail of St. Agnes icon, compliments of St. Isaac of Syria Skete, www.skete.com.