White tie

White tie, or formal evening dress is strictly regulated, and properly comprises:

• Black tailcoat with silk (grosgrain or satin) facings, horizontally cut-away at the front
• Black trousers with a single stripe of satin or braid in the US or two stripes in Europe; trousers are fish-tail back, thus worn with braces instead of a belt.
• White plain stiff-fronted cotton shirt (usually cotton marcella (US: piqué))
• White stiff-winged collar
• White bow tie (usually cotton marcella (US: piqué))
• White low-cut waistcoat (usually cotton marcella (US: piqué), matching the bow tie and shirt, which should not extend below the front of the tailcoat)
• Black silk stockings (long socks)
• Black court shoes

From http://en.wikipedia.org/wiki/White_tie