A creature's alignment broadly describes its moral and personal attitudes. (58) Alignment is a combination of two factors: one identifies morality (good, evil, or neutral), and the other describes attitudes toward society and order (lawful, chaotic, or neutral). Thus, nine distinct alignments define the possible combinations.
A creature's alignment provides a clue to its disposition and how it behaves in a social or combat situation. For example, a chaotic evil monster might be difficult to reason with and might attack characters on sight, whereas a neutral monster might be willing to negotiate. (255)
Note of Caution. Each alignment describes the typical behavior of a creature with that alignment, but individuals might vary significantly from that typical behavior, and few are perfectly and consistently faithful to the precepts of their alignment.
A player character can be of any alignment. The alignment specified in a monster’s stat block is the default; feel free to depart from it and change a monster’s alignment to suit the needs of your campaign. (255)