An over-arching brand encompassing multiple editions and game systems, including half-editions and the early "advanced" and "basic" games, that have been called "Dungeons & Dragons".
In general, the timeline for Dungeons and Dragons roughly follows this:
1974 Dungeons & Dragons (original white box edition with three booklets)
1977 AD&D Monster Manual (AD&D 1st edition)
1977 Dungeons & Dragons (2nd version - blue box set)
1978 AD&D Players Handbook (AD&D 1st edition)
1979 AD&D Dungeon Master Guide (AD&D 1st edition)
1981 Dungeons & Dragons (3rd version - Basic and Expert sets in magenta/light blue)
1983 Dungeons & Dragons (4th version - Basic and Expert sets in red/blue)
1989 AD&D 2nd Edition Released
1991 Dungeons & Dragons (5th version - Single Boxed Set)
2000 Dungeons & Dragons 3rd edition Released
2003 Dungeons & Dragons 3.5 edition Released
2008 Dungeons & Dragons 4th edition Released
2012 Dungeons & Dragons Next is announced as in development