When We line couples up for the introduction into the reception,there is often confusion as to which side the bridesmaids and groomsmen stand. It is common to keep the same sides that you lined up during the ceremony.
The Brides and Bridesmaids traditionally go on the left and Groom and Groomsmen line up on the right.
The tradition actually stems back to the Middle Ages when Brides were traded and sold for Marriage. In other traditions the Brides family would often provide gifts and dowry and bring that to the ceremony. The Groom and his Groomsman needed to keep their right hands, which was their sword hand, free to protect the bride and their party from bandits and thieves that would attempt to steal her or the dowry. The bride probably won’t be stolen at a modern wedding but this tradition has kept true hundreds of years later.