Dungeons & Dragons is a fantasy tabletop role-playing game (RPG) originally designed by Gary Gygax and Dave Arneson. It was first published in 1974 by Tactical Studies Rules, Inc. (TSR). It has been published by Wizards of the Coast since 1997. The game was derived from miniature wargames, with a variation of the 1971 game Chainmail serving as the initial rule system. D&D's publication is commonly recognized as the beginning of modern role-playing games and the role-playing game industry.
Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface is land consisting of continents and islands. The remaining 71% is covered with water, mostly by oceans but also by lakes, rivers, and other fresh water, which together constitute the hydrosphere. Much of Earth's polar regions are covered in ice. Earth's outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates Earth's magnetic field, and a convecting mantle that drives plate tectonics.
February 25 is the 56th day of the year in the Gregorian calendar. 309 days remain until the end of the year.
In mathematics, an integral assigns numbers to functions in a way that describes displacement, area, volume, and other concepts that arise by combining infinitesimal data. The process of finding integrals is called integration. Along with differentiation, integration is a fundamental operation of calculus, and serves as a tool to solve problems in mathematics and physics involving the area of an arbitrary shape, the length of a curve, and the volume of a solid, among others.
The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows periodic trends. The seven rows of the table, called periods, generally have metals on the left and nonmetals on the right. The columns, called groups, contain elements with similar chemical behaviours. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases. Also displayed are four simple rectangular areas or blocks associated with the filling of different atomic orbitals.
Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc. for Windows and macOS. It was originally created in 1988 by Thomas and John Knoll. Since then, the software has become the industry standard not only in raster graphics editing, but in digital art as a whole. The software's name has thus become a generic trademark, leading to its usage as a verb although Adobe discourages such use. Photoshop can edit and compose raster images in multiple layers and supports masks, alpha compositing and several color models including RGB, CMYK, CIELAB, spot color, and duotone. Photoshop uses its own PSD and PSB file formats to support these features. In addition to raster graphics, Photoshop has limited abilities to edit or render text and vector graphics, as well as 3D graphics and video. Its feature set can be expanded by plug-ins; programs developed and distributed independently of Photoshop that run inside it and offer new or enhanced features.
In mathematics, the Taylor series of a function is an infinite sum of terms that are expressed in terms of the function's derivatives at a single point. For most common functions, the function and the sum of its Taylor series are equal near this point. Taylor's series are named after Brook Taylor who introduced them in 1715.
A chess opening or simply an opening refers to the initial moves of a chess game. The term can refer to the initial moves by either side, White or Black, but an opening by Black may also be known as a defense. There are dozens of different openings, and hundreds of variants. The Oxford Companion to Chess lists 1,327 named openings and variants. These vary widely in character from quietpositional play to wild tactical play. In addition to referring to specific move sequences, the opening is the first phase of a chess game, the other phases being the middlegame and the endgame.
Washington, D.C., formally the District of Columbia and also known as D.C. or just Washington, is the capital city of the United States of America. It is located on the Potomac River bordering Maryland and Virginia, with Congress holding its first session there in 1800. The city was named for George Washington, the first president of the United States and a Founding Father, and the federal district is named after Columbia, a female personification of the nation. As the seat of the U.S. federal government and several international organizations, the city is an important world political capital. It is one of the most visited cities in the U.S., with over 20 million visitors in 2016.
Pound sterling, known in some contexts simply as the pound or sterling, is the official currency of the United Kingdom, Jersey, Guernsey, the Isle of Man, Gibraltar, South Georgia and the South Sandwich Islands, the British Antarctic Territory, and Tristan da Cunha. It is subdivided into 100 pence. The Pound sterling is the oldest currency in continuous use. Some nations that do not use sterling also have currencies called the pound.
The Douglas C-47 Skytrain or Dakota is a military transport aircraft developed from the civilian Douglas DC-3 airliner. It was used extensively by the Allies during World War II and remained in front-line service with various military operators for many years.
The Sicilian Defence is a chess opening that begins with the following moves:
The Queen's Gambit is the chess opening that starts with the moves:
SHA-2 is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression function itself built using the Davies–Meyer structure from a specialized block cipher.
Climate change includes both global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century, humans have had unprecedented impact on Earth's climate system and caused change on a global scale.
Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group are vitamin D3 (also known as cholecalciferol) and vitamin D2 (ergocalciferol).
Marvel's Agents of S.H.I.E.L.D. is an American television series created by Joss Whedon, Jed Whedon, and Maurissa Tancharoen for ABC, based on the Marvel Comics organization S.H.I.E.L.D., a peacekeeping and spy agency in a world of superheroes. It is set in the Marvel Cinematic Universe (MCU) and acknowledges the continuity of the franchise's films and other television series. The series was produced by ABC Studios, Marvel Television, and Mutant Enemy Productions, with Jed Whedon, Tancharoen, and Jeffrey Bell serving as showrunners.