The alignment system is a two-dimensional grid, one axis of which measures a "moral" continuum between good and evil, and the other "ethical" between law and chaos. Those characters that fall on one of the extremes are "good" or "evil", "lawful" or "chaotic"; in addition, there is a middle ground of "neutrality" on both axes, describing characters that are indifferent, committed to balance, or conflicted about the struggle between good and evil (or law and chaos). By combining the two axes, any given character has one of nine possible alignments.
Certain classes are restricted in the sorts of alignment they can take. A paladin traditionally must be of lawful good alignment; rogues and barbarians are seldom lawful in alignment. Clerics and other priests must typically uphold the alignments favoured by their deities. Druids must be wholly or partially neutral in their allegiances. Assassins are usually evil. These restrictions have been somewhat relaxed in the 3rd and 5th editions of the Dungeons & Dragons game, although a character's alignment may shift if he acts in marked variance from his declared alignment.
In the 4th edition of the game, this axis was simplified to only five sets of moral principles, shown below. Besides, the "neutral" axis was removed and the class restriction was dropped completely, except for members of divine classes. For example, clerics should have an alignment close to their god unless they or their god is unaligned, and paladins must be aligned exactly as their patron deity.
The original two-axis alignment system was restored in the 5th edition of the game.
- Bruce Cordell. Excerpts: Alignment. 4th Edition Player's Handbook. "Being unaligned is not the neutral alignment of previous editions."
- Rob Heinsoo, Andy Collins, James Wyatt (June 2008). Player's Handbook 4th edition. (Wizards of the Coast), p. 19. ISBN 0-7869-4867-1.
- Rob Heinsoo, Andy Collins, James Wyatt (June 2008). Player's Handbook 4th edition. (Wizards of the Coast), pp. 61–2. ISBN 0-7869-4867-1.
- Rob Heinsoo, Andy Collins, James Wyatt (June 2008). Player's Handbook 4th edition. (Wizards of the Coast), pp. 90–1. ISBN 0-7869-4867-1.
- Mike Mearls, Jeremy Crawford (2014). Player's Handbook 5th edition. (Wizards of the Coast), p. 122. ISBN 978-0-7869-6560-1.