Short answers, pulled from the story.
The dwarf first appeared as a playable character in the original 1974 edition of Dungeons and Dragons. This emergence occurred from the wargame Chainmail where miniature figures of varying sizes were used together for the first time.
Dwarves average four feet in height with stout, broad bodies. Male dwarves grow thick facial hair, while the depiction of female dwarves has varied significantly over the decades depending on the specific campaign setting.
Dwarves generally worship Moradin, whom they believe is their creator. According to their legends, Moradin fashioned the dwarves into a likeness of himself using gems and metal before breathing life into them.
More than a dozen subraces of dwarf have been described over the history of Dungeons and Dragons publications and rules editions. These include hill dwarves, mountain dwarves, deep dwarves, duergar, and gully dwarves among others.
The concept of the dwarf draws a direct lineage from Norse and Teutonic mythology, specifically from the Germanic story The Ring of the Nibelungen and the Brothers Grimm fairy tale Rumpelstiltskin. The early version of the dwarf was also heavily influenced by Poul Anderson's 1961 novel Three Hearts and Three Lions.
Unique dwarf subraces appear in settings such as Athas, Dragonlance, Forgotten Realms, World of Greyhawk, and Spelljammer. Athasian dwarves stand less than 5 feet tall and have no hair, while gully dwarves live in ruined cities and sewers.