Galen said:
Everything. Why there are groomsmen there, why the guy doesn't have the rings, why people make speechs, why there are vows, what goes on during a ceremony... I don't know about the whole thing or the planning that goes into it.
Nearly every widely practiced wedding custom is seated in old tradition or superstition.
The white wedding dress--Not only does white symbolize purity and virginity, but it was also thought to ward off evil spirits.
The wedding veil—It is speculated that the tradition of wearing a veil came from one of two possibilities: it is a throw-back to the time when the groom would throw a blanket over the head of the woman of his choice when her captured her and carted her off, or when marriages were arranged, the bride’s face would be covered until the ceremony was complete, so it would be too late for the groom to run off if he didn’t like the look of his bride.
The term “bride”—The word itself is old English, and was a name for ‘cook.’
Bridesmaids and groomsmen—The tradition of having both bridesmaids and ushers present during a ceremony derives from the Roman law that mandated there be ten witnesses present at the ceremony for the purpose of fooling the evil spirits who were believed to cause mischief. The bridesmaids and groomsmen would be dressed in clothing matching identical to the bride and groom, thus keeping the evil spirits from figuring out who was actually getting married.
Bridal shower—When a father did not approve of his daughter’s marriage, some of the local townspeople would come together and give the bride an assortment of household items to be used as a dowry.
Flowers—The presence of flowers in the wedding ceremony symbolizes fertility, new life and never ending love.
Tossing the bouquet—In England it was believed that the bride could pass along her good fortune to others.
Attendants and spectators to the weddings would try to tear away pieces of the bride's clothing and flowers in hopes of gaining some of this fortune. Often times the bride would toss her bouquet into the crowd to distract them in her attempt to get away. Thus it became commonplace for the bride to toss the bouquet and it was believed that the woman who caught it would be the next to be blessed with marriage.
The kiss—In Roman times a kiss was seen as a legal bond that sealed all contracts, and has become a staple ending to a wedding ceremony.
White aisle runner—This is supposed to symbolize God’s holiness and walking on holy ground. It is believed that by having this runner present in the place of marriage, God will be actively involved in the ceremony.
The “ring finger”—The Greeks believed that the third finger was connected to the heart by the “vein of love.” Thus this finger became the place for the ring in Western weddings.
The brides placement to the left— When a bridegroom secured his bride and prepared to marry her, she was placed to his left in order to protect her, leaving his right hand free for swordplay if need be.
The honeymoon— Originally, when the groom “kidnapped” his bride he would take her into hiding. Usually, by the time the bride’s family found her, she would already be pregnant and a price for her would then be negotiated.
The term “tying the knot”—This dates back to Roman times when the bride would wear a girdle that had been tied in many knots which the groom would have to untie.
Throwing rice—Rice was a symbol of fertility and a wish for a “full pantry.” Bubbles, confetti or flower petals have since been replaced rice because of its danger to birds that eat it.
Carrying the bride over the threshold—It was tradition for the bride to enter the house through the front door before the groom, and if she tripped or stumbled it was seen to be very bad luck, hence it became a duty for the groom to carry his new bride over the threshold.
http://mimi.essortment.com/originswedding_rrnp.htm