An oikos (ancient Greek: , plural: ; English prefix: eco- for ecology and economics) is the ancient Greek equivalent of a household, house, or family. An oikos was the basic unit of society in most Greek city-states, and included the head of the oikos (usually the oldest male), his extended family (wife and children), and slaves living together in one domestic setting. Large oikoi also had farms that were usually tended by the slaves, which were also the basic agricultural unit of the ancient economy. The Greek oikos differed significantly from the Roman domus in architectural layout, a...

Strained yogurt, yogurt cheese, labneh, or Greek yogurt is yogurt which has been strained in a cloth or paper bag or filter to remove the whey, giving a consistency between that of yogurt and cheese, while preserving yogurt's distinctive sour taste. Like many yogurts, strained yogurt is often made from milk which has been enriched by boiling off some of the water content, or by adding extra butterfat and powdered milk. However most strained yogurt have no added fats and are made of real milk. Yogurt strained through muslin is a traditional food in the Levant, Eastern Mediterranean, Nea...

Night clouds or noctilucent clouds are tenuous cloud-like phenomena that are the "ragged-edge" of a much brighter and pervasive polar cloud layer called polar mesospheric clouds in the upper atmosphere, visible in a deep twilight. They are made of crystals of water ice. Noctilucent roughly means night shining in Latin. They are most commonly observed in the summer months at latitudes between 50° and 70° north and south of the equator. They can only be observed when the Sun is below the horizon. They are the highest clouds in Earth's atmosphere, located in the mesosphere at altitudes of a...

:This article is about the cannon salute. For the three-shot rifle salute given at military and law enforcement funerals, see Three-volley salute. Gun salutes are the firing of cannons or firearms as a military honor. The custom stems from naval tradition, where a warship would fire its cannons harmlessly out to sea, until all ammunition was spent, to show that it was disarmed, signifying the lack of hostile intent. As naval customs evolved, 21 guns came to be fired for heads of state, with the number decreasing with the rank of the recipient of the honor. While the 21-gun salute is th...