Wedding rings symbolize commitment and marital status.
We usually were rings in the third finger, so why?
There are many theories as to why this particular finger came to symbolize marriage. Both the ancient Romans and Egyptians believed that a vein - called the vena amoris in Latin - ran directly from that finger to the heart.
In medieval England, a bridegroom would slide the ring part way up his bride's thumb, index and middle finger, saying "In the name of the father, the son, and the holy ghost" as he passed each one. He then put the ring on the next available finger - the third finger of the left hand. This practice was finally formalized in the 1500's when Henry VIII's son authored The Book of Common Prayer, which gives English modern Protestant wedding vows and decrees on which finger our wedding rings should go.
Now we know that as the ring represents the true love and commitment, so we love to were it in heart, really.