There are many parties and events which require guests to dress up in a particular theme or dress code, and for most of the formal events, black tie has been, and still is, a popular choice. However, even this dress code has many variants. These were introduced keeping in mind those people who don't find it wise to spend a lot of money on purchasing a tuxedo.
The black tie attire originated in England around 1860. It wasn't considered to be a formal dress code in those days, and would be worn at semi-formal events and occasions. In fact, the white tie dress code was considered to be the formal one. Given below are the three basic variations.
This attire includes a classic black tuxedo, pleated tuxedo shirt, black trouser pants, black bow tie, cuff links, studs, a vest or a cummerbund, and black shoes. If this dress code is specifically mentioned on the invite, then wearing a tuxedo is a given, and no other attire will do. Women have a relatively wider choice, as the attire can either be a three quarter length or floor-length evening gown. Even a short, dressy cocktail dress (depending on the time of the occasion and current fashion) looks good when paired with the right jewelry, a hand bag or a clutch of either silk, satin, velvet, or brocade, and a suitable pair of sandals or pumps.
Black Tie Preferred
This dress code is used in the invites when the host expects the guests to wear a dark suit and a tie, if not a tuxedo, to the event. This option was introduced keeping in mind people who genuinely could not afford to own or rent a tuxedo, or those who did not want to spend too much money on one. The term simply suggests that a tuxedo would be preferred, but a dark suit and a tie will also do. However, it should not be more informal than that.
Black Tie Invited or Optional
Both these terms mean the same thing. Unlike the first two, here the host does not insist on men wearing tuxedos. They can either choose to wear tuxedos or wear a dark suit, preferably black or dark gray, with a white dress shirt; and instead of a bow tie, a necktie can do. It is better to opt for silk neckties with solid colors instead of patterns. A solid-colored tie gives it the look of an ensemble for a formal event or occasion. As the term suggests, this dress code gives men an option of choosing between typical formal wear, a tuxedo, or a simple formal suit. Also, women can freely choose to wear either a short, dressy cocktail dress or a three quarter length dress, as both these types of dresses have a formal look.
When you are invited to a party with a black tie optional dress code, your choice of attire widens and there are more options for you to choose from. Thus, it is the most flexible among the black tie dress codes.