Usually the guests to the wedding wear dresses. It is not necessary that it should be very long, the only exception is a formal event, colors can also be absolutely anything, except white.
At an informal wedding held in the first half of the day, it is possible to wear an elegant business suit. If the celebration is held in the evening, welcome cocktail or any fancy dress can be little black dress, but it should not be very long. On semi-formal daytime wedding allowed to wear a short dress or suit for the evening would be appropriate cocktail dress.
The official event, held in the morning allows you to wear a suit or a short beautiful dress. Optionally, you can complement the look with a hat and gloves. Evening appropriate long or short elegant dress with stylish accessories or a luxurious stole. If after the official part of evening reception is planned, then will need a long beautiful dress, can't hurt and a large number of sequins, fur, diamonds, gold.
You are invited as a guest, not a bridesmaid, so don't wear clothes in white. Good manners suggest in a day is not to compete with the bride. Also, do not wear dark or black outfit and use the sequins for a day event. The Shine will make you look too dressy.
Don't worry about what your outfit will be the same color as that of any other guest, after all, impossible to foresee. Try to choose a feminine and decent attire, be respectful to the guests. Club style, overly provocative clothing is not suitable for wedding. If your chosen transparent clothes, strapless or simply suggests the propriety, so the outfit has to be changed. Long Opera gloves, reaching to the top of the hands, are allowed to wear only a dress without sleeves. And don't forget to remove them when eating or drinking.
If you came to a wedding invitation does not specify the degree of formality of the event. A suit of delicate pastel shades or feminine dress with a floral pattern in the morning, or a little black dress after six o'clock will be the right option.
Even going to an informal holiday, do not forget about common sense when getting dressed. For example, for weddings on the beach good beautiful summer sundress, but it will be inappropriate jeans or shorts.