Daylight saving time in the United States is the practice of setting the clock forward by one hour during the warmer part of the year, so that evenings have more daylight and mornings have less. Most areas of the United States observe daylight saving time (DST), the exceptions being Arizona (except for the Navajo, who do observe daylight saving time on tribal lands), Hawaii, and the overseas territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United States Virgin Islands. The Uniform Time Act of 1966 established the system of uniform Daylight Saving Time throughout...

Most areas in North America and Europe, and some areas in the Middle East, observe daylight saving time (DST), while most areas of Africa and Asia do not. In South America, most countries in the north of the continent near the equator do not observe DST, while Paraguay and southern parts of Brazil do. The practice of observing daylight saving time in Oceania is also mixed, with New Zealand and parts of southeastern Australia observing DST, while most other areas do not. == Observance as of 2018 == == See also == Time zone UTC offset Lists of time zones Daylight saving time in the Americas Summer...

February 30 occurs on some calendars but not the Gregorian calendar, where the month of February contains only 28 days, or 29 days in a leap year. February 30 is usually used as a sarcastic date for referring to something that will never happen or will never be done. February 31 may also be used in such a fashion. == Swedish calendar == February 30 was a real date in Sweden in 1712. Instead of changing from the Julian calendar to the Gregorian calendar by omitting a block of consecutive days, as had been done in other countries, the Swedish Empire planned to change gradually by omitting all leap...

The Doomsday rule is an algorithm of determination of the day of the week for a given date. It provides a perpetual calendar because the Gregorian calendar moves in cycles of 400 years. The Doomsday algorithm for mental calculation was devised by John Conway in 1973 after drawing inspiration from Lewis Carroll's perpetual calendar algorithm. It takes advantage of each year having a certain day of the week, called the doomsday, upon which certain easy-to-remember dates fall; for example, 4/4, 6/6, 8/8, 10/10, 12/12, and the last day of February all occur on the same day of the week in any year....