A holiday is a day or other period of time set aside for festivals or recreation. Public holidays are set by public authorities and vary by state or region. Religious holidays are set by religious organisations for their members and are often also observed as public holidays in religious majority countries. Some religious holidays such as Christmas have become or are becoming secularised by part or all of those who observe it. In addition to secularisation, many holidays have become commercialised due to the growth of industry.

Holidays can be thematic, celebrating or commemorating particular groups, events or ideas, or non-thematic, days of rest which do not have any particular meaning. In Commonwealth English, the term can refer to any period of rest from work, such as vacations or school holidays. In American English, the holidays typically refers to the period from Thanksgiving to New Year's, which contains many important holidays in American culture.