According to I Do OBX, the wedding website of Outer Banks Wedding Officiant, when a bride walks down the aisle, it signals the couples' transition from being single to being married. Additionally, the members of the wedding procession are displaying their support for the union.
Although there are variations for the wedding march, the traditional format begins with the groom, best man and officiant waiting at the end of the aisle. The bridesmaids and groomsmen begin the procession, walking in pairs. Then comes the maid or matron of honor. If a ring bearer and flower girl are included, they appear next. Finally, the bride and her escort, typically but not necessarily her father, close the sequence.