What Does "black Tie Optional" Mean?
On an invitation, "black tie optional" means that men at the party may wear black tuxedos but are not required to. However, in many less formal settings, "black tie optional" is used as a shorthand way of suggesting guests dress in a "business casual" fashion.
In formal settings, "black tie" means wearing full black tuxedos for men and formal dresses for women. Many high-class parties require or strongly recommend this attire. When a party is designated as "black tie optional," less formal attire is also acceptable, although it should still be quite elegant. For example, a full black suit with a matching tie and shoes is also acceptable; a tuxedo that is not black is also appropriate.
Other parties are "black tie creative," which invites a bit more flexibility within a formal dress code. Often, this means wearing a traditional black tuxedo but swapping out portions of the outfit. For example, a black tuxedo with a black dress shirt is a creative form of black tie attire.
The term "black tie" is sometimes used more informally to suggest that guests dress nicely without necessarily requiring tuxedos. For example, inviting guests to a black tie birthday party tells them they should get at least a little dressed up.