The day has finally arrived. You received an invitation to a gala event. You are important enough to hobnob with some snobby people, network, and advance your career. The invitation has all the pertinent details—the date, the time, the place—and one additional line specifying black tie. “Easy enough,” you think to yourself, “I have one of those for funerals, sure I'll wear it to this event.” You put on your suit, your black tie, but when you arrive—and much to your surprise—no one else looks like you. They're all in tuxedos. You've committed a grievous error and, while everyone is too polite to comment on it, the look from your boss makes it clear that you have made a dire mistake. It is the last time you'll be invited to one of these events as you clearly can't be trusted to do it properly. The opportunity is over, your career in ruins, and all of it could all have been avoided had you known a few pieces of information.
The term black tie means tuxedo. If you're like me, you haven't owned or even worn a tuxedo since high school or the last time you were part of a wedding party. Mine was for band, and it was a relatively cheap thing, certainly nothing that would fit now nor would I choose to wear. Similarly, renting a tuxedo is an option if you only need it for a single event. Even then, you can learn what to look for to look as good as possible. I can't recommend buying or customizing your own tuxedo unless you're going to be wearing it often enough to justify the expense.
Colors. You may think a tuxedo is like a Ford Model T: you can get it in any color you want, as long as it's black. Black is the classic color, and you will not go wrong wearing it. Some dress codes may be strict enough to only allow a black tuxedo, but it isn’t the only option. Even the classic guidelines allow for a white jacket in hot and humid environments, and wearing one would be my choice in DC. A modern, striking option is a midnight blue tuxedo that stands out just enough from the surrounding black. We can dream about the suits we could wear if we only had places to wear them and the money to afford them. You may also see some tuxedos with different colored accents, such as a white jacket with black lapels and outlines around the pockets. This look is gimmicky rather than classy, something you would see at a wedding party or something and entertainer might wear, not the picture of sophisticated grace.
Jacket. A tuxedo jacket has several required elements to it. A proper one only comes with peak lapels, but shawl is sometimes acceptable. The facing of the lapels will also be made with a glossier finish. For buttons, you'll probably only see one on the front of the jacket, and it should be covered in the suit fabric; the same is true for the surgeon’s cuff buttons. The pockets on the waist of the jacket will probably be welted to yield a cleaner look.
Pants. The only difference between the pants you wear with a tuxedo and any other suit is that the tuxedo pants have a stripe of glossy material, the same used for the lapel facing, running down the outside of the legs.
Cummerbunds and Waistcoats. A real tuxedo is always a three-piece suit. For some reason, it's considered informal to show a belt or waistband. You can cover-up in two ways. A cummerbund is an oval-like structure that is attached around your waist. It also has some corrugations, almost like you could stick credit cards in them. The other option is simply a waistcoat. My personal preference would be the waistcoat, because it stays up better and a cummerbund just kind of looks weird and silly. You might see some versions of a tuxedo with a waistcoat but only the front part. These will loop around the neck and only show on the front, but as soon as you take off the jacket the mirage is revealed. I can't recommend such things, because what's the point of half a garment?
Shirt. The tuxedo shirt has several differentiators from your typical white button down. For one, the collars have a specific tip design not seen on other shirts. Instead of traditional buttons, you'll have little pegs that act like cufflinks. You can add some texture via corrugations running top to bottom on either side of the buttonholes. You really only need one of these shirts in your wardrobe and that's only if you even wear tuxedos often.
Shoes. The traditional pairing is patent leather black shoes. I am not a fan because, to reiterate, patent leather looks a little plasticky, cheap, and ridiculous.
Tie. The reason it's called black tie is because you always wear a black bow tie with it. Never wear a necktie.
Alternatives. Let's say you're invited to an event on very short notice and you can't get a rental (or you don't want to go through the trouble). One option is to repurpose your black suit if it has enough features to mimic the tuxedo. If that suit has three pieces, peak lapels, and you wear an appropriate shirt and black bow tie, no one should give you a second glance. They're also not likely going to make a big stink of it in public even if they do notice. And go ahead and wear your more comfortable, if not so intensely glossy, black shoes, they shouldn't notice those either.
You may come across references to several other types of formalwear. You'll most likely never have to wear any of them, so we'll get these marginal suits quickly.
Dinner Jacket. A dinner jacket is somewhere between the tuxedo and your regular suit in formality. Shawl lapels are viable options here, as are a wide variety of different colors and patterns. The classic deep red burgundy smoking jacket falls into this category. The only issue is that I am hard-pressed to think of a situation where you would even need to wear a dinner jacket in the 21st century. Classify it under the category of cool to own but probably not worth it.
Morning Dress. This Victorian in anachronism no longer exists unless you are one of two people: a Solicitor of the United States arguing before the Supreme Court or a groomsman for your obnoxious friend who chose a very formal midday wedding. In the latter case, consider getting a better friend.
White Tie. Think black tie, but you wear a white bow tie and, instead of a jacket, you wear a frock coat. No one who owns a smartphone should be wearing tails. The only reason you should ever wear this ensemble is if it's required to attend a very important event. the only two I can think of would be a state dinner and accepting a Nobel prize. That won't be most of us, so don't worry about it and toss those tail coats in the trash.