The symbolism of the wedding ring actually varies from one culture to another. The overall symbolic nature of the wedding ring can be seen as one continuous and seamless circle indicating the continuous expectation of the marriage.
Alternatively, it can be seen as a ring placed on the finger as a sense of "ownership." Wedding ring symbolism and meaning has changed over the years and continues to evolve over time.
Throughout history there have been magical connotations associated with the wearing of rings. They were once considered to have protective or magical powers of protection for anyone who wore them. Blessing them or chanting and canting were considered to be an additional protective power. In traditional wedding ceremonies of almost all denominations the rings are blessed before they are exchanged. This practice dates back to the days where the rings offered protection.
Why do we place a wedding ring on the left hand? Why do we wear it on the third finger? Not all customs agree with this philosophy and there are ample cultures that wear the wedding ring on the right hand. The origin of such a tradition can be traced back to Ancient Rome. The Romans were convinced that this finger contained a specified artery that ran uninterrupted from the hand to the heart. This artery was thought to be only in the third finger of the left hand.