Several different editions of the Dungeons & Dragons (D&D) fantasy role-playing game have been produced since 1974. The current publisher of D&D, Wizards of the Coast, produces new materials only for the most current edition of the game. However, many D&D fans continue to play older versions of the game and some third-party companies continue to publish materials compatible with these older editions.

After the original edition of D&D was introduced in 1974, the game was split into two branches in 1977: the rules-light system of Dungeons & Dragons and the more complex, rules-heavy system of Advanced Dungeons & Dragons (AD&D). The standard game was eventually expanded into a series of five box sets by the mid-1980s before being compiled and slightly revised in 1991 as the Dungeons & Dragons Rules Cyclopedia. Meanwhile, the 2nd edition of AD&D was published in 1989. In 2000 the two-branch split was ended when a new version was designated the 3rd edition, but dropped the "Advanced" prefix to be called simply Dungeons & Dragons; a revision, called "v3.50 was released in 2003.The 4th edition was published in 2008. The 5th edition was released in 2014. A revision of the 5th edition was published in 2024.

The original D&D was published as a box set in 1974 and features only a handful of the elements for which the game is known today: just three character classes (fighting-man, magic-user, and cleric); four races (human, dwarf, elf, and hobbit); only a few monsters; only three alignments (lawful, neutral, and chaotic). With a production budget of only $2000 to print a thousand copies, the result has been described as amateurish.

Only $100 was budgeted for artwork, and TSR co-founder Gary Gygax pressed into service anyone who was willing to help, including local artist Cookie Corey; Greg Bell, a member of Jeff Perren's gaming group; D&D co-creator Dave Arneson; Gygax's wife's half-sister Keenan Powell; and fellow TSR co-founder Don Kaye. Each artist was paid $2 for a small piece or $3 for a larger piece, with an identical amount paid as a royalty every time another thousand copies were printed.

The rules assume that players own and play the miniatures wargame Chainmail and use its measurement and combat systems. An optional combat system is included within the rules that later developed into the sole combat system of later versions of the game. In addition, the rules presume ownership of Outdoor Survival, a board game by then-unaffiliated company Avalon Hill for outdoor exploration and adventure. D&D was a radically new gaming concept at the time, and it was difficult for players without prior tabletop wargaming experience to grasp the vague rules. The release of the Greyhawk supplement removed the game's dependency on the Chainmail rules, and made it much easier for new, non-wargaming players to grasp the concepts of play. It also inadvertently aided the growth of competing game publishers, since just about anyone who grasped the concepts behind the game could write smoother and easier-to-use rules systems and sell them to the growing D&D fanbase (Tunnels & Trolls being the first such).

Supplements such as Greyhawk, Blackmoor, Eldritch Wizardry and Gods, Demi-Gods & Heroes, published over the next two years, greatly expanded the rules, character classes, monsters and spells. For example, the original Greyhawk supplement introduced the thief class, and weapon damage varying by weapon (as opposed to character class). In addition, many additions and options were published in the magazines The Strategic Review and its successor, The Dragon.

An updated version of D&D was released between 1977 and 1979 as Advanced Dungeons & Dragons (AD&D). The game rules were reorganized and re-codified across three hardcover rulebooks, compiled by Gary Gygax, incorporating the original D&D rules and many additions and revisions from supplements and magazine articles. The three core rulebooks are the Monster Manual (1977), the Player's Handbook (1978), and the Dungeon Master's Guide (1979). Major additions include classes from supplements like assassin, druid, monk, paladin, and thief, while bard, illusionist, and ranger, which had previously only appeared in magazine articles, were added to the core rulebooks. An alignment system with nine alignments is used, rather than the previous three-alignment system in the original D&D rules.

Later supplements for AD&D include Deities & Demigods (1980), Fiend Folio (another book of monsters produced semi-autonomously in the UK - 1981), Monster Manual II (1983), Oriental Adventures, Unearthed Arcana (1985), which mostly compiles material previously published in Dragon magazine, and others.