"White Tie" is a simple two-word code for the formality of
dress required. White Tie (also known as evening dress) is
the most formal dress code that exists today. (The
semi-formal counterpart is known as black tie. The formal
daytime equivalent is known as morning dress.) For men,
"White Tie" means to wear a tux with tails. If one doesn't
have a tux, a dark suit or other dressy attire is
appropriate. For ladies, "White Tie" usually means a long
dress but may also simply mean that "dressy clothing" is
appropriate.