Frock coat in the context of "Tuxedo"

A suit, also called a lounge suit, business suit, dress suit, or formal suit, is a set of clothes comprising a suit jacket and trousers of identical textiles generally worn with a collared dress shirt, necktie, and dress shoes. A skirt suit is similar, but with a matching pencil skirt instead of trousers. It is currently considered semi-formal wear or business wear in contemporary Western dress codes; however, when the suit was originally developed it was considered an informal or more casual option compared to the prevailing clothing standards of aristocrats and businessmen. The lounge suit originated in 19th-century Britain as sportswear and British country clothing, which is why it was seen as more casual than citywear at that time, with the roots of the suit coming from early modern Western Europe formal court or military clothes. After replacing the black frock coat in the early 20th century as regular daywear, a sober one-coloured suit became known as a lounge suit.

Suits are offered in different designs and constructions. Cut and cloth, whether two- or three-piece, single- or double-breasted, vary, in addition to various accessories. A two-piece suit has a jacket and trousers; a three-piece suit adds a waistcoat. Hats were almost always worn outdoors (and sometimes indoors) with all men's clothes until the counterculture of the 1960s in Western culture. Informal suits have been traditionally worn with a fedora, a trilby, or a flat cap. Other accessories include handkerchief, suspenders or belt, watch, and jewelry.

A top hat (also called a high hat, or, informally, a topper) is a tall, flat-crowned hat traditionally associated with formal wear in Western dress codes, meaning white tie, morning dress, or frock coat. Traditionally made of black silk or sometimes grey, the top hat emerged in Western fashion by the end of the 18th century. Although such hats fell out of fashion through the 20th century, being almost entirely phased out by the time of the counterculture of the 1960s, it remains a formal fashion accessory. A collapsible variant of a top hat, developed in the 19th century, is known as an opera hat.

Perhaps inspired by the early modern era capotain, higher-crowned dark felt hats with wide brims emerged as a country leisurewear fashion along with the Age of Revolution around the 1770s. Around the 1780s, the justaucorps was replaced by the previously casual frocks and dress coats. With the introduction of the top hat in the early 1790s, the tricorne and bicorne hats began falling out of fashion. By the start of the 19th century, the directoire style dress coat with top hat was widely introduced as city wear for the upper and middle classes in all urban areas of the Western world. The justaucorps was replaced in all but the most formal court affairs. Around the turn of the 19th century, although for a few decades beaver hats were popular, black silk became the standard, sometimes varied by grey ones. While the dress coats were replaced by the frock coat from the 1840s as conventional formal daywear, top hats continued to be worn with frock coats as well as with what became known as formal evening wear white tie. Towards the end of the 19th century, whereas the white tie with black dress coat remained fixed, frock coats were gradually replaced by morning dress, along with top hats.

Formal wear or full dress is the Western dress code category applicable for the most formal occasions, such as weddings, christenings, confirmations, funerals, Easter and Christmas traditions, in addition to certain state dinners, audiences, balls, and horse racing events. When formal dress is required, generally permitted alternatives include the most formal versions of ceremonial dresses (including court dresses, diplomatic uniforms and academic dresses), full dress uniforms, religious clothing, national costumes, and most rarely frock coats (which preceded morning coat as default formal day wear 1820s-1920s). In addition, formal wear is often properly worn when displaying official full size orders and medals.

The protocol specifying men's traditional formal wear has remained virtually unchanged since the early 20th century. Despite decline following the counterculture of the 1960s, it remains observed in formal settings influenced by Western culture: notably around Europe, the Americas, South Africa, Australia, as well as Japan. For women, although fundamental customs for formal ball gowns (and wedding gowns) likewise apply, changes in fashion have been more dynamic. Traditional formal headgear for men is the top hat, and for women picture hats etc. of a range of interpretations. Shoes for men are dress shoes, dress boots or pumps, and for women heeled dress pumps. In western countries, a "formal" or white tie dress code typically means tailcoats for men and evening dresses for women. The most formal dress for women is a full-length ball or evening gown with evening gloves. Some white tie functions also request that the women wear long gloves past the elbow.

White tie, also called full evening dress or a dress suit, is the most formal evening Western dress code. For men, it consists of a black tail coat (alternatively referred to as a dress coat, usually by tailors) worn over a white dress shirt with a starched or piqué bib, white piqué waistcoat and the white bow tie worn around a standing wing collar. Mid or high-waisted black trousers with galon, a braid of trim consisting of two silk stripes to conceal the outer seams of the trousers, along with court shoes (British English) (pumps in American English) complete the outfit. Orders, decorations and medals in miniature may be worn. Acceptable accessories include a black top hat, white gloves, a white scarf, a pocket watch, a white pocket square, and a boutonnière. Women wear full-length ball or evening gowns with evening gloves and, optionally, tiaras, jewellery, and a small handbag.

The dress code's origins can be traced back to the end of the 18th century. New fully black-coloured justaucorps styles emerged around the Age of Revolution, notably adopted by the bourgeois third estate of the Estates General of the Kingdom of France. Increasingly following the French Revolution, high society men abandoned the richly decorated justaucorps coats for more austere cutaway dress coats in dark colours, with cuts perhaps further inspired by the frocks and riding coats of country gentlemen. Gradually replacing also breeches, lacy dress shirts and jabots with plain white dress shirts, shorter waistcoats, white cravats and pantaloons, this became known as directoire style. By the early 19th-century Regency era, dark dress tailcoats with light trousers became standard daywear, while black and white became the standard colours for evening wear. Although the directoire style was replaced for daytime by black frock coats and bowties by mid-19th century, cutaway black dress tailcoats with white bowtie has remained established for formal evening wear ever since.