Proper wedding attire depends on the event's time of day and location as well as the wishes of the engaged couple. For a traditional wedding that is held in the late afternoon or evening, a man can wear a suit and a woman can wear a cocktail dress or a top with either a skirt or dress pants.
Look to the invitation for clues about appropriate dress. If the invitation says "white tie," guests are expected to dress as formally as possible. That means a man should wear a tuxedo with tails and a white bow tie and a woman should wear a ball gown.
If the invitation states that the wedding is "black tie," a man should wear a tuxedo and a woman should wear a long gown or a cocktail dress in a neutral tone. Sometimes a couple uses the words "black tie optional" or "formal," which means men should wear tuxedos or dark suits and women should wear long gowns or cocktail dresses.
When the wedding is very informal, the invitation may include words such as "dress for the beach" or "casual," which means a man can wear a collared shirt with dress pants and a woman can wear a sundress or a dressy top and pants.
If the invitation doesn't clearly state any dress code, or if guests have questions about what's expected, the engaged couple or their close family members can provide more direction.