The bowler hat, also known as a Coke hat, billycock, bob hat, bombín (Spanish) or derby, is a hard felt hat with a rounded crown, originally created by the London hat-makers Thomas and William Bowler in 1849. It has traditionally been worn with semi-formal and informal attire. The bowler, a protective and durable hat style, was popular with the British, Irish, and American working classes during the second half of the 19th century, and later with the middle and upper classes in the United Kingdom, Ireland, and the east coast of the United States.

Informal wear or undress, also called business wear, corporate/office wear, tenue de ville or dress clothes, is a Western dress code for clothing defined by a business suit for men, and cocktail dress or pant suit for women. On the scale of formality, it is considered less formal than semi-formal wear but more formal than casual wear. Informal or undress should not be confused with casual wear such as business casual or smart casual; most situations calling for “informal wear” will usually tolerate casual dress to varying extents.