Alignments describe an individual's basic personalitity. There are 3 basic sub-alignments: Lawful, Neutral, and Chaotic; and 3 basic main alignments: Good, Neutral, and Evil.
A Lawful Good character typically acts with compassion, and always with honor and a sense of duty.
Lawful Good characters may sometimes find themselves faced with the dilemma of whether to obey law or good when the two conflict—for example, upholding a sworn oath when it would lead innocents to come to harm.
A Neutral Good character is guided by his conscience and typically acts altruistically, without regard for or against Lawful precepts such as rules or tradition. A Neutral Good character has no problems with co-operating with lawful officials, but does not feel beholden to them. In the event that doing the right thing requires the bending or breaking of rules, they do not suffer the same inner conflict that a Lawful Good character would.
A Chaotic Good character favors change for a greater good, disdains bureaucratic organizations that get in the way of social improvement, and places a high value on personal freedom, not only for oneself, but for others as well. They always intend to do the right thing, but their methods are generally disorganized and often out of alignment with the rest of society. They may create conflict in a team if they feel they are being pushed around, and often view extensive organization and planning as pointless, preferring to improvise.
A Lawful Neutral character typically believes strongly in Lawful concepts such as honor, order, rules and tradition, and often follows a personal code. Examples of Lawful Neutral characters might include a soldier who always follows orders, a judge or enforcer that adheres mercilessly to the word of the law, a disciplined monk, and an assassin who lives by a set of morals and does not prey on the innocent.
This alignment represents Neutral on both axes, and tends not to feel strongly towards any alignment. A farmer whose primary overriding concern is to feed his family is of this alignment. Most animals, lacking the capacity for moral judgment, are of this alignment since they are guided by instinct rather than conscious decision. Many roguish characters who play all sides to suit themselves are also of this alignment (such as a weapon merchant with no qualms selling his wares to both sides of a war for a profit).
A character of this alignment is an individualist who follows his or her own heart, and generally shirks rules and traditions. Although they promote the ideals of freedom, it is their own freedom that comes first. Good and Evil come second to their need to be free, and the only reliable thing about them is how totally unreliable they are. Chaotic Neutral characters are free-spirited and do not enjoy the unnecessary suffering of others, but if they join a team, it is because that team's goals happen to coincide with their own at the moment. They invariably resent taking orders and can be very selfish in their pursuit of personal goals. A Chaotic Neutral character does not have to be an aimless wanderer; they may have a specific goal in mind, but their methods of achieving that goal are often disorganized, unorthodox, or entirely unpredictable.
Characters of this alignment see a well-ordered system as being easier to exploit, and show a combination of desirable and undesirable traits; while they usually obey their superiors and keep their word, they care nothing for the rights and freedoms of other individuals and are not averse to twisting the rules to work in their favor. Examples of this alignment include tyrants, undiscriminating mercenary types who have a strict code of conduct, and loyal soldiers who enjoy the act of killing.
Characters of this alignment are typically selfish and have no qualms about turning on their allies-of-the-moment. They have no compunctions about harming others to get what they want, but neither will they go out of their way to cause carnage or mayhem when they see no direct benefit to it. They abide by laws for only as long as it is convenient for them. A villain of this alignment can be more dangerous than either Lawful or Chaotic Evil characters, since he is neither bound by any sort of honor or tradition nor disorganized and pointlessly violent.
Characters of this alignment tend to have no respect for rules, other people's lives, or anything but their own desires, which are typically selfish and cruel. They set a high value on personal freedom, but do not have any regard for the lives or freedom of other people. They do not work well in groups, as they resent being given orders, and usually behave themselves only out of fear of punishment.
It is not compulsory for a Chaotic Evil character to be constantly performing sadistic acts just for the sake of being evil, or constantly disobeying orders just for the sake of causing chaos. They do however enjoy the suffering of others, and view honor and self-discipline as weaknesses.