Maid of honor: Also known as a matron of honor if she is married, this is the bride's right-hand-girl. She helps the bride plan the wedding, and supports her during the ceremony.
Best man: The male equivalent to a maid of honor. He helps plan the bachelor party, making sure things don't go in a direction disrespectful of the bride. He traditionally drives the groom to the wedding, keeps the bride's ring, gives the officiator his or her fee after the ceremony, and offers a reception toast.
Wedding Bridesmaids: A support group for the bride and the maid of honor, they help her organize pre-wedding parties and perform nuptial tasks. It is the bridesmaids who throw the bride a bachelorette party.
Flower girl: A young girl, typically aged three to eight, who walks in front of the bride with a basket of flower petals, which she scatters about. After walking down the aisle, the flower girl sits down for the duration of the ceremony.
Ring bearer: A young boy, typically aged three to eight, who walks down the aisle just before or with the flower girl -- or in front of the bride if there is no flower girl.
Groomsmen: Any number of men who help the best man and the groom with wedding plans. At the ceremony, the groomsmen accompany the bridesmaids down the aisle. Gift Ideas for your Wedding Attendants & Other Cool Wedding Stuff.