The tradition of wearing the wedding ring on the ring finger of the left hand originally came from the Roman notion that there was a vein in that finger, the “Vein of Love,” that was believed to be directly connected to one’s heart. This practice has remained despite the fact that scientists have proven that this is false (maybe it is because we all have a little hopeless romantic in us).
Another theory behind a wedding ring’s placement comes from religion. The thumb, index finger and the middle finger have historically symbolized the Trinity, therefore the ring finger was the next important finger to display allegiance to one another and the marriage behind God.
On a more practical level, some believe wedding rings are worn on the left hand because the rings are traditionally made of soft metals. Since a large portion of the world is right-handed, a wedding ring is less likely to be damaged on one’s left hand. Therefore it is protected in the way you should protect your marriage.
In most Western cultures the wedding ring is worn on the left hand. Although in some European cultures (i.e. Germany, Norway, Poland), wedding rings are worn on the right hand instead of the left. Once again, because many people are right-handed, they believe that placing it on the right hand shows that the marriage is more prominent and more important in their lives. Some Europeans wear rings on their left hand prior to the marriage and then transfer it over to their right hand as a part of the wedding ceremony.