1. Giving away the bride. This comes from the days when women were considered their father's property until they got married and then became their husband's property. The bride was literally "given away" in exchange for a payment, or dowry.
2. Not seeing each other before the wedding. This tradition dates back to the time of arranged marriages, where it was thought that if couples saw each other before the wedding, they might bail.
3. Wearing a veil. People in ancient Rome believed evil spirits would be attracted to the bride, so they covered her face with a veil to help hide her and confuse them.
4. Sitting on the bride or groom's "side" for the ceremony. In Christian weddings, the bride's family sits on the left, the groom's sits on the right. But if the point is to become one family, does it even matter?