A holiday is a day set aside by custom or by law on which normal activities, especially business or work including school, are suspended or reduced. Generally, holidays are intended to allow individuals to celebrate or commemorate an event or tradition of cultural or religious significance. Holidays may be designated by governments, religious institutions, or other groups or organizations. The degree to which normal activities are reduced by a holiday may depend on local laws, customs, the type of job held or personal choices.

The concept of holidays often originated in connection with religious observances. The intention of a holiday was typically to allow individuals to tend to religious duties associated with important dates on the calendar. In most modern societies, however, holidays serve as much of a recreational function as any other weekend days or activities.

In many societies there are important distinctions between holidays designated by governments and holidays designated by religious institutions. For example, in many predominantly Christian nations, government-designed holidays may center on Christian holidays, though non-Christians may instead observe religious holidays associated with their faith. In some cases, a holiday may only be nominally observed. For example, many Jews in the Americas and Europe treat the relatively minor Jewish holiday of Hanukkah as a "working holiday", changing very little of their daily routines for this day.

The word holiday has differing connotations in different regions. In the United States the word is used exclusively to refer to the nationally, religiously or culturally observed day(s) of rest or celebration, or the events themselves, whereas in the United Kingdom and other Commonwealth nations, the word may refer to the period of time where leave from one's duties has been agreed, and is used as a synonym to the US preferred vacation. This time is usually set aside for rest, travel or the participation in recreational activities, with entire industries targeted to coincide or enhance these experiences. 

The days of leave may not coincide with any specific customs or laws. Employers and educational institutes may designate ‘holidays’ themselves which may or may not overlap nationally or culturally relevant dates, which again comes under this connotation, but it is the first implication detailed that this article is concerned with.

Winter in the Northern Hemisphere features many holidays that involve festivals and feasts. The Christmas and holiday season surrounds the Christmas and other holidays, and is celebrated by many religions and cultures. Usually, this period begins near the start of November and ends with New Year's Day. Holiday season in the US corresponds to the period that begins with Thanksgiving and ends with New Year's Eve. Some Christian countries consider the end of the festive season to be after the feast of Epiphany.

Other secular (non-religious) holidays are observed nationally, internationally (often in conjunction with organizations such as the United Nations), and across multi-country regions. The United Nations Calendar of Observances dedicates decades to a specific topic, but also a complete year, month, week and days. Holidays dedicated to an observance such as the commemoration of the ending of World War II, or the Shoah, can also be part of the reparation obligation as per UN General Assembly Resolution 60/147 Basic Principles and Guidelines on the Right to a Remedy and Reparation for Victims of Gross Violations of International Human Rights Law and Serious Violations of International Humanitarian Law.

The right to freedom of expression is recognized as a human right under article 19 of the Universal Declaration of Human Rights (UDHR) and recognized in international human rights law in the International Covenant on Civil and Political Rights (ICCPR). Article 19 of the UDHR states that "everyone shall have the right to hold opinions without interference" and "everyone shall have the right to freedom of expression; this right shall include freedom to seek, receive and impart information and ideas of all kinds, regardless of frontiers, either orally, in writing or in print, in the form of art, or through any other media of his choice." The version of Article 19 in the ICCPR later amends this by stating that the exercise of these rights carries "special duties and responsibilities" and may "therefore be subject to certain restrictions" when necessary "[f]or respect of the rights or reputation of others" or "[f]or the protection of national security or of public order (order public), or of public health or morals.