Holiday refers to the day set apart for religious observance or for the commemoration of some extraordinary event total stoppage of work and normal business activities, including feasting, parades and carnivals, or displays of flags and speechmaking.

Originally, in ancient times, holidays were predominantly religious in character and linked to natural events such as the annual course of the sun or the phases of the moon. The word "holiday", in fact, is derived from "holy day". Subsequently, secular holidays commemorating historical occasions or distinguished persons outnumbered holy days, although many ancient religious rituals and customs have been carried over into modern times and incorporated into both secular and religious observations. Today, the outstanding holiday is one of religious observance and abstention from normal work routines, taking place on Sunday for Christians, Friday for Muslims, and Saturday for Jews. In the U.S., Sunday is not only a religious holiday but is also the only common-law holiday.

National holidays are set aside by official government proclamation to celebrate such occasions as the achievement of independence, the founding of the nation, the adoption of a constitution, the birthday of the ruler, or the national patron saint's day.

The U.S. has no national holidays as such legal holidays-on which banks, schools, or other public institutions and most places of business are closed-are designated by legislative enactment or by executive proclamation. Congress and the president designate the legal holidays for the District of Columbia and the federal territories but are without power to declare national holidays. Independence Day and other holidays are observed on a national scale as a result of action by the calendar date and requests national observance, and the states then usually enact the necessary legislation. Federal statutes often specify certain days as holidays for purposes related to the legislation.

In order to give federal employees three-day weekends, a 1968 federal law made several changes in dates of holiday observances, effective in 1971: Washington's Birthday now falls on the third Monday in February; Memorial Day, on the last Monday in May; Columbus Day, on the second Monday in October. Individual states later adopted these Monday holidays.

A number of states commemorate important events in their history. In Vermont, for example, the Battle of Bennington, fought in the American Revolution, is commemorated annually on August 16; in Louisiana the Battle of New Orleans of the War of 1812 is commemorated on January 8; Patriot's Day, commemorating the first battle of the American Revolution, is celebrated on or about April 19 in Massachusetts and Maine; and several southern states celebrate a confederate Memorial Day on different days in the spring.