When planning an event as important as your wedding, it is so important to be clear with your guests about what they should wear. Your event should capture your vision, and this must be communicated to your friends and family from the start.
Black tie is usually meant for formal evening weddings. This means that you expect the gentlemen to wear tuxedos and ladies to don a cocktail dress or long gown.
A formal wedding means that men do not have to wear tuxes, but they could choose this option. A dark-colored suit and tie would also be acceptable, though. For a formal wedding, ladies should wear a long gown, a cocktail-length formal dress, or a nice suit.
If you are having a beach formal wedding, it means your event will be outdoors, literally on the beach. For men, a summer-weight suit in a light color is appropriate. For women, a formal sundress with cute, sand-friendly sandals is the best choice.
Semi-formal weddings sometimes vary depending upon what time of day the wedding is to be held. For daytime events, lighter colors and a slightly more casual style are acceptable. However, for an evening semi-formal wedding, guests should wear darker colors and have a more formal look. This translates as dark suits and cocktail dresses.
For a more relaxed wedding, suggest that guests wear business casual clothing. This means men should wear dress pants with a polo or a button-down shirt, and women could opt for a sundress, a blouse with a skirt, or dress pants.
Guests who are not directly involved with the wedding planning (so probably most of your guests) will need wardrobe guidance from the bride and groom. Be sure to include this information on your website or with your invitations!