A day set aside by a nation or culture (in some cases, multiple nations and cultures) typically for celebration but sometimes for some other kind of special culture-wide (or national) observation or activity.
- Yom Kippur (Day of Atonement)
- Passover
- Rosh Hashanah (Spiritual New Year)
- Purim (Based on the events in the Biblical book of Esther)
- Sukkot (The Feast of Tabernacles)
- Hannukah (also: Chanukah; the Feast of Lights)
- Tu B'shevat (New year of the trees)
- Purim
- Yom HaShoah (Holocaust remembrance day)
- Yom Ha'atzma'ut (Israel independence day)
- Shavuot (The Feast of Weeks)
- Tisha B'Av
Christian holidays:
Islamic/Muslim holidays
National holidays:
- United States
- New Years Day (January 1)
- Martin Luther King Day (third Monday in January)
- President's Day (third Monday in February)
- Memorial Day (fourth Monday in May; originally May 30)
- Independence Day (July 4)
- Labor Day (first Monday in September)
- Columbus Day (second Monday in October; originally October 12)
- Veteran's Day (second Monday in November; originally November 11)
- Thanksgiving (fourth Thursday in November)
Other holidays:
- Boxing day (December 26)
- Halloween (October 31)
- New Year's Day - January 1
- Valentine's Day February 14
- Worker's Day or May Day (most countries - United States and Canada are prominent exceptions)
In the United Kingdom and Ireland, a holiday is also a period spent away from home or business in travel or recreation (e.g., "I'm going on holiday to Majorca next week"), like an American "vacation".
BTW, we need to add all those national holiday articles, recently added to Wikipedia, to this page.