Black tie is a dress code that is also known as tuxedo, dinner jacket, and cravate noire. When the master of ceremony decides his guests should come in black tie, you will wear a tuxedo, French cuffed white tuxedo shirt (preferably with black buttons from the navel up), bow tie, suspenders (no belt), polished black shoes (varnish is optional), long black socks. A tuxedo vest, cummerbund and pocket square are optional. The self tie bow tie looks much better and will be appreciated by the connoisseurs. At the end of the night when you are lounging at the pool, you may untie the bow tie and hang it around your neck like Craig Daniel in the photo below.
Black tie is always after sundown and gentleman do not wear watches (use your cell phone if you really need to know the time). Your pockets should contain few items such as some paper money and perhaps a credit card. The ticket pocket of your tuxedo jacket is great for storing coins. You may offer the lady to carry some of her items in your pockets.
A tuxedo should be from wool, have silk lapels, fit snugly and needs to make you feel confident. Renting a tuxedo that does not look good on you may ruin the night. Never ever should one wear a boutonnière and a pocket square simultaneously. Boutonnières are more appropriate for white tie. White tuxedos should only be worn in warm climates.