Daylight saving time (DST)—also summer time in British English— is the practice of advancing clocks during the lighter months so that evenings have more apparent daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn.
The modern idea of daylight saving was first proposed in 1895 by George Vernon Hudson and it was first implemented by Germany and Austria-Hungary starting on 30 April 1916. Many countries have used it at various times since then. Much of the United States used DST in the 1950s and 1960s, and DST use expanded following the 1970s energy crisis. It has been widely used in North America and Europe since then.
Daylight saving time (DST) by country, showing an overview of current usage and some history by country. For more detailed observations by country and continent please consult the continent level articles:
Most areas of North America and Europe 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 Chile, Paraguay, and Uruguay and southern parts of Brazil do. Oceania is also mixed, with New Zealand and parts of southern Australia observing DST, while most other areas do not.
European Summer Time is the arrangement in Europe by which clocks are advanced by one hour in spring and moved back in autumn, to make the most of seasonal daylight (also called daylight saving time). This is done in all of the countries of Europe except Iceland, Belarus, and Russia. Summer Time was first introduced in some countries during the First World War, then largely abandoned with some exceptions, mostly during the Second World War, until the 1960s and 70s when the energy crisis prompted a wide scale re-introduction. The practice has been fully coordinated across the continent since 1996.
The period extends from 01:00 UTC on the last Sunday in March until 01:00 UTC on the last Sunday in October each year.
Science of drugs including their origin, composition, pharmacokinetics,
pharmacodynamics, therapeutic use, and toxicology.
Pharmacology (from Greek φάρμακον, pharmakon, "poison" in classic Greek; "drug" in modern Greek; and -λογία, -logia "study of", "knowledge of") is the branch of medicine and biology concerned with the study of drug action, where a drug can be broadly defined as any man-made, natural, or endogenous (within the body) molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.