The Vikings were seafaring north Germanic people who raided, traded, explored, and settled in wide areas of Europe, Asia, and the North Atlantic islands from the late 8th to the mid-11th centuries. The Vikings employed wooden longships with wide, shallow-draft hulls, allowing navigation in rough seas or in shallow river waters. The ships could be landed on beaches, and their light weight enabled them to be hauled over portages. These versatile ships allowed the Vikings to travel as far east as Constantinople and the Volga River in Russia, as far west as Iceland, Greenland, and Newfoundland, and as far south as Nekor. This period of Viking expansion, known as the Viking Age, constitutes an important element of the medieval history of Scandinavia, Great Britain, Ireland, Russia, and the rest of Europe.

Since 1944, the County of Los Angeles Department of Parks and Recreation has been meeting the diverse needs of not only residents, but also visitors from around the world. With over 63,000 acres of parks, gardens, lakes, trails, natural areas, and the world's largest public golf course system, the Department of Parks and Recreation is committed to providing the public with social, cultural, and recreational activities to enjoy the whole year.

Speed skating is a competitive form of ice skating in which the competitors race each other in traveling a certain distance on skates. Types of speed skating are long track speed skating, short track speed skating, and marathon speed skating. Short track speed skating takes place on a smaller rink, normally the size of an ice hockey rink. Distances are shorter than in long track racing, with the longest Olympic race being 3000 meters. Races are usually held as knockouts, with the best two in heats of four or five qualifying for the final race, where medals are awarded. Disqualifications and falls are not uncommon. The sport originates from pack-style events held in North America and was officially sanctioned in the 1970s, becoming an Olympic sport in 1992. Although this form of speed skating is newer, it is growing faster than long track speed skating, largely because short track can be done on an ice hockey rink rather than a long-track oval.

The Mayan languages form a language family spoken in Mesoamerica and northern Central America. Mayan languages are spoken by at least 6 million indigenous Maya, primarily in Guatemala, Mexico, Belize and Honduras. In 1996, Guatemala formally recognized 21 Mayan languages by name, and Mexico recognizes eight more. The Mayan language family is one of the best documented and most studied in the Americas. Modern Mayan languages descend from Proto-Mayan, a language thought to have been spoken at least 5,000 years ago.

Plasma is one of the four fundamental states of matter (the others being solid, liquid, and gas). Heating a gas may ionize its molecules or atoms (reducing or increasing the number of electrons in them), thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions.