Dungeons & Dragons (commonly abbreviated as D&D or DnD) 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 (now a subsidiary of Hasbro) 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.
The early success of D&D led to a proliferation of similar game systems. Despite the competition, D&D has remained the market leader in the role-playing game industry. In 1977, the game was split into two branches: the relatively rules-light game system of basic Dungeons & Dragons, and the more structured, rules-heavy game system of Advanced Dungeons & Dragons (abbreviated as AD&D). AD&D 2nd Edition was published in 1989. In 2000, a new system was released as D&D 3rd edition, continuing the edition numbering from AD&D; a revised version 3.5 was released in June 2003. These 3rd edition rules formed the basis of the d20 System, which is available under the Open Game License (OGL) for use by other publishers. D&D 4th edition was released in June 2008. The 5th edition of D&D, the most recent, was released during the second half of 2014.
D&D has gone through multiple editions, with various changes to the rules and nomenclature. The game is set in a medieval fantasy world in which multiple players form a group that is led through an adventure by one player who assumes the role of the storyteller, or Dungeon Master. The Dungeon Master makes up story events or chooses them from one of the published adventures, to which the players may respond in different manners to create a unique gaming experience.
The other players each choose a race (e.g. human, elf, dwarf, halfling), a class (e.g. Fighter, Rogue, Wizard), and skills for their character, and they apportion a small number of points to different attributes (Constitution, Strength, Dexterity, Intelligence, Wisdom, and Charisma) that determine how effective a character is in performing various actions. As actions are performed successfully, points are gained to the corresponding attributes. Most complex actions have some probability of failing, which is determined by rolling one or more of the game’s polygonal dice (4-, 6-, 8-, 10-, 12-, and 20-sided). Often players use a sheet marked with a grid and miniature figurines to represent their characters’ movements.
In the Dungeons & Dragons game, magic is a force of nature and a part of the world. Since the publication of Advanced Dungeons & Dragons (1977), magic has been divided into two main types: arcane, which comes from the world and universe around the caster, and divine, which is inspired from above (or below): the realms of gods and demons.
Many kinds of monsters in D&D can be classified into typologies based on their common characteristics, and various books and game guides have been produced focusing on specific kinds of monsters. Gamer Keith Ammann, in his book, "The Monsters Know What They're Doing: Combat Tactics for Dungeon Masters" examines thirteen such groupings, those being "humanoids", "monstrosities", "dragons", "giants", "undead", "aberrations", "fiends", "celestials", "fey", "elementals", "constructs", "oozes and plants", and "beasts". There is some flexibility within these groupings. For example, many kinds of creatures can become undead (once-living things that have died, and since been restored to a lifelike state through magic), or can be used to form magical constructs.