Both the wedding ring and engagement ring are worn on the third, or ring, finger of the left hand, and, according to the rules of proper etiquette, the wedding ring goes on first. Wedding-ring fashions change over time, but the wedding ring, which is a concrete symbol of the marriage, is always worn closest to the heart.
The exchange of rings is a formal sign that the marriage contract, or pact, has been sealed. Wedding or marriage rings can be found in all ancient cultures. The third finger of the left hand was chosen because ancient cultures believed a vein connected that finger directly to the heart.
In 1549, England's King Edward VI decreed that the third finger of the left hand be designated as the "official" ring finger, and the Book of Common Prayer confirmed it by designating the left hand as the marriage hand.
During the Ceremony
The exchange of a ring or rings is a part of the marriage ceremony; the current practice is known as a "double-ring" ceremony, with both the bride and groom receiving a ring. In a religious ceremony, the officiant blesses the rings. During the ceremony, the groom may choose to place only the wedding ring on the bride's finger or both the wedding and engagement ring, in the correct order, of course.
The bride may choose to wear her engagement ring on her right hand during the ceremony and move it to her left hand afterward, or the groom can place both rings on her finger during the ceremony. The rings traditionally are kept by the groom, the best man, the maid (or matron) of honor or the ring bearer prior to their use in the ceremony.