The system of alignments for the 4th (current) edition of Dungeons and Dragons includes five alignments: Lawful Good, Good, Unaligned, Evil, and Chaotic Evil. The original edition of DND from the 1970s decade included three alignments: Lawful, Neutral, and Chaotic. The 2nd edition of DND (called Advanced Dungeons and Dragons) had nine alignments, Lawful Good, Neutral Good, Chaotic Good, Neutral, Lawful Neutral, Chaotic Neutral, Lawful Evil, Neutral Evil, and Chaotic Evil. The 2nd edition's alignment system was used by 3rd edition DND as well.
If someone wants to use an alignment system from an older version of DND for a game that otherwise uses 4th edition rules, use the conversion chart below:
4th edition 2nd/3rd edition original edition
Lawful Good Lawful Good Lawful
Good Neutral or Chaotic Good Lawful
Unaligned Lawful, True, or Chaotic Neutral Neutral
Evil Lawful or Neutral Evil Chaotic
Chaotic Evil Chaotic Evil Chaotic