The circular ring, symbolizing undying and unending love, is traditionally worn on the third finger on the left, hand. This finger was chosen based on the Greek belief that the artery from that finger flows directly to the heart. Placing the ring on the vena amoris, or love vein, thereby joined the couple’s destiny. Early Christians are believed to have chosen the third finger on the left hand because when you touch the ring to three fingers while repeating, "In the name of the Father, of the Son, and the Holy Ghost", it lands on the third finger.
Another theory as to why the wedding ring is worn on the left hand is that when the groom faces his bride and reaches out with his right hand (as most people are right-handed), he naturally touches her left hand. During the Elizabethan era, wedding rings were placed on the third finger of the left hand at the marriage ceremony and then moved to the thumb after the ceremony, In India, wedding rings were only worn for a few days after the ceremony. Since a wedding ring was considered a luxury, it was often only worn a short time and then melted down to make something more useful.
The practice of men wearing wedding rings did not become popular until World War II. Up until this time, only the bride wore a wedding ring. Many couples married in anticipation of a long separation and wedding bands, one for each partner, were considered critical to the war effort. They represented comfort to the lonely soldier and as a reminder to the bride of her husband.