Black Tie - White Tie Invitation Definition

Today, BLACK TIE means formal attire, not specifically to wear a black tie.

Invitations to special events and formal affairs will indicate what type of formal attire is expected.
Although the clothing industry is trendy, there are some definite rules.

Black Tie

It is generally accepted that "Black Tie" requires formal attire. Take advantage of this opportunity to truly look and feel your very best in a tuxedo.
Today, " Black Tie " means formal attire, not specifically to wear a black tie.
Men wear tuxedos, women wear cocktail, long dresses or dressy evening separates.

White Tie

If the Invitation says "White Tie" or "Full Dress"

Means ultra-formal. You can step into the glittering special occasion looking dashing and proper in a traditional tailcoat. Wear a white wing collar shirt, a white pique vest, white tie, and black trousers accented by the formal satin stripe. Complete your outfit with patent shoes. Women wear long gowns.

Black Tie Preferred

If the Invitation says "Black Tie Preferred"

Indicates that the host prefers guests to wear formal evening attire to the special occasion. Black Tuxedo, White Tie Dinner Jacket (mid-April through Labor Day) or a dark contemporary style tuxedo are acceptable (no Tailcoats). Non formal Dress Suits are also acceptable, but not preferred by the host.

Black Tie Optional

If the Invitation says "Black Tie Optional"

Is not as strong a statement for formal attire as "Black Tie" or "Black Tie Preferred," yet formal dress is wholly appropriate and acceptable. Styles may include Black Tuxedo, White Dinner Jacket (mid-April through Labor Day) or a dark contemporary style Tuxedo (no Tailcoats).

Black Tie Invited

If the Invitation says "Black Tie Invited"

Is a phrase appearing more frequently than "preferred" or "optional." It is usually in the context of large gatherings of civic or business groups, such as a dinner sponsored by the Chamber of Commerce. It states that gentlemen attending are welcome to dress in formal attire if they would like, but it is not required. Styles for these affairs are the same as for "Black Tie Optional."
Women wear cocktail, long dresses or dressy evening separates.

Semi Formal

In strict and very proper social circles, "Semi Formal" means "Black Tie." However, today, if a host wants his guests to wear Black Tuxedos, he will generally use the phrase "Black Tie Event."

"Semi-Formal" allows any style of Tuxedo or Dinner Jacket. This is where knowledge of your local community, common sense and good taste come into play.

An evening wedding (after 6 PM) would still dictate dark suits for him, and a cocktail dress for her. Daytime semi formal events mean a suit for him and an appropriate short dress or dressy suit for her.
As a general rule, if a lady wears a floor length gown, it is appropriate for her escort to wear formal attire.

Cocktail Attire

Means short, elegant dresses for her and dark suits for him.

Dressy Casual

Usually means no jeans or shorts. Similar to business casual, but a tad dressier.

Casual

Generally means anything goes.

Informal

Can mean the same as casual. However, when associated with a wedding or other special event, some form of decorum and good taste should prevail. A dress for her or a nice pair of slacks and shirt for him are informal, but respectful of the event.

courtesy of http://fashion.about.com

Being fashionable dressed is not as much a matter of how expensive or trendy your clothes are.
It is how you wear your clothes and how you combine color and textures that determine your flair for fashion.