On this day in history

From English Wikipedia's date articles (“October 9”, “February 29” and so on), which volunteer editors maintain with sources. We take a snapshot when the site is built, keep every anniversary Wikipedia's editors selected for the date plus the entries whose own article exists in the most language editions (an entry without one counts by the least covered article it links), and link every entry to its article so you can check the details.

Each page keeps every anniversary Wikipedia's editors selected for the date, then fills up to about 25 events, 20 births and 15 deaths with the entries whose own article (the event's, or the person's or thing's it is about) exists in the most language editions; an entry without one counts by the least covered article it links, and a place never counts on its own. That favours globally known topics; a nationally important event can be left out. A handful of widely known events that the editors do not select are kept by hand, and on a few dates the event the day is best known for is put first by hand. The full list is always one click away on Wikipedia.

Not necessarily. Wikipedia usually gives older events in the calendar used at the time — mostly the Julian calendar — so the day number can differ from a modern date by ten days or more.

Yes. February 29 has its own page; the people born on leap day celebrate their actual birthday only once every four years.

The history lists are Wikipedia text under CC BY-SA 4.0, so you can reuse them if you credit Wikipedia and share under the same licence. The calendar facts and holiday lists are ours; see the terms.