In D&D, moral alignment is described along two axes: the first includes "lawful", "neutral", and "chaotic"; the second is "good", "neutral", "evil". A person or organization has an alignment with two components, one from each set, and there are 9 possible combinations.
Here are brief descriptions of how people from all nine alignments will tend to behave.
Lawful good -- You like law and order, and you try to obey the law at all times while working for good causes. Stereotype: the good, honest judge; Superman.
Lawful neutral -- Whether the consequences are good or bad, all that matters to you is that the laws are obeyed. Stereotype: the obsessive-compulsive district attorney; Robocop.
Lawful evil -- You work within the law to accomplish your own evil ends. You may be honorable, in the sense that you keep your word, but you are solely concerned with looking out for yourself. Stereotype: evil corporate lawyer.
Neutral good -- You don't really care whether the law is obeyed or not; you're mostly concerned that the results are good. Stereotype: Batman.
True neutral -- You don't care what happens, as long as balance is maintained and no one bothers you. Stereotype: no such people exist; stoners.
Neutral evil -- You don't care what aeffect your actions have on others or how you fit into society, as long as you get what you want. Stereotype: most criminals.
Chaotic good -- You dislike law and society, but still try to do good. Stereotype: Robin Hood.
Chaotic neutral -- You try to sow disorder and chaos wherever you go, without any regard for good or evil. Stereotype: sociopaths, psychotics.
Chaotic evil -- You try to undermine society and order, while working to bring about your own evil agenda. Stereotype: just about every supervillain.
[This post is mainly for use as a reference, in case I want to refer to D&D alignments later.]