Wedding receptions typically occur after the wedding ceremony and are more party-like events. They are not as formal as the ceremony itself, but still are considered formal events. Most often, guests will wear the same clothes they did at the wedding for the reception afterwards.
Business casual attire is appropriate for a wedding reception. It allows you to maintain a professional appearance while still allowing you to enjoy the festivities. A suit may be overly restrictive, but a business casual outfit with sport coat will allow you to move around, dance and enjoy the event.
Wedding receptions are synonymous with dancing - wear something you can move around in
Lots of pictures will be taken, so look good
Wear comfortable shoes you can dance in