When the invitation says: 'Black Tie'
If the event you are attending is 'black tie' and the invitation says the same, you are expected to wear a tuxedo. All guests invited to this function are required and expected to wear formalwear. However, this term does not mean you have to wear a black tie!

When the invitation says: 'Black Tie Preferred'
This means the host of the party prefers to see all guests in formalwear. You could wear a dark suit, but tuxedos are preferred.

When the invitation says: 'Black Tie Invited or Optional'
In this case, it is not mandatory to wear a tuxedo, however, you will probably see more tuxedos than dark suits at these affairs. Black tuxedos and white or ivory dinner jackets with black trousers are appropriate. However, dinner jackets should only be worn between Memorial Day and Labor Day.

When the invitation says: 'White Tie'
This term means you must wear black tails with black trousers and a white pique' formal shirt, bow tie and vest. This ensemble is known as the 'ultra formal look' and if your event calls for it, you should not wear anything else!

What to wear on a Cruise
Many cruises will have a formal event when formal wear is appropriate. It may not be required, but it is suggested that you wear a tuxedo. Any black tuxedo will be suited for a cruise with the exception of tailcoats. Dinner jackets are great choices as well. If you have multiple formalwear nights on your cruise, consider a black tuxedo and a dinner jacket!