Summarize:

Whether for a wedding, prom, or formal event, the tuxedo is a classic look that exudes style. The tux in its most basic form sports simple lines similar to a normal man's suit, but with the addition of silk bands on the outside hem of each trouser leg. The lapels on the jacket are also often fashioned with silk, helping to provide a more formal look.  In the contemporary US, tuxedos are usually considered the “gold standard” for formal wear. It might surprise you, however, that tuxes – called black tie attire for the black bowtie – are neither the most formal in men’s dress wear nor always appropriate for important occasions. Historically, there is a sort of hierarchy of menswear. Tuxedos actually grew out of was, for the time, relaxed evening wear as an alternative to the tailed frock coat. “Black tie,” then, is only one kind of “formal wear,” the other being the even more formal “white tie,” a similar outfit with white bowtie, tails, and often tophat.  White tie attire is usually reserved for the most fancy or formal events, like debutante balls, state dinners, and galas. Keep in mind that black tie is also not “day wear.” According to tradition, events that occur during the evening call for either white or black tie, while daytime events call for day wear like morning dress or a man’s business suit.  Morning suits are worn more often in Britain and feature a black or grey cutaway or morning coat, non-matching grey trousers—sometimes striped, buff waistcoat, tie, and often tophat.  Morning suits also come in a hierarchy, from formal morning dress to less formal morning suit and even the semi-formal “stroller,” which has no tails. When will your upcoming event occur? In general if your event is during the daytime, you should go with day wear like a morning suit. If it is after dark, you are safe to go with black or white tie formal evening wear. The rule governing the proper forms of dress has to do with when the event ends. So, for example, if you are attending a wedding that starts during the day but ends after sundown, you can choose evening wear. Often event invitations will give instructions on dress. Pay close attention to the wording so that you can determine whether or not you will need a tuxedo. Parsing the language can sometimes take a bit of effort.  For instance, an invitation calling for “formal wear” does not necessarily mean a tux. Formal wear refers to a complete suit – tie, cuff links, and the works – but, as noted, can also include white tie or morning wear. A black tie event means that you will be expected to wear a tux, so get ready for fittings. Showing up in anything else would be a faux pas. “Black tie optional” means just that – if you’d like, you can wear a tuxedo. “Semi-formal” is a notch down from formal, and means that tuxedos are not required. Here, you’d be better to settle on a dark suit for evening events.
Figure out if “black tie” is right for you. Learn to tell the tuxedo apart from other forms of dress attire. Note the time of day. Check your invitation.