Lawful Good
Lawful Good character are boy scouts. They believe in justice and beneviolence in its highest form, because of this, they can not so much as jaywalk.
Neutral Good
Neutral Good characters are generally good, but, will not go out of their way to bring villians to justice.
Chaotic Good
Chaotic Good characters do what they believe is right regardless of the law. Robin Hood is a classic example of this.
Lawful Neutral
Lawful Neutral character believe in law and order but are not concerned with morality. A judge would be lawful neutral.
Neutral
Neutral characters do not seek justice or chaos nor good or evil believeing that they extremes are dangerous.
Chaotic Neutral
Chaotic Neutral characters are individualists. They believe in their own liberties, but, will not strive to protect the liberties of others.
Lawful Evil
Lawful Evil characters are villians with honor. While they do seek evil they do so with in the limits of their own code of conduct. Some may have a moral code against killing innocents for example.
Neutral Evil
Neutral Evil characters are self-serving and do whatever they can get away with.
Chaotic Evil
Chaotic Evil characters spread evil and chaos whereever they go often commiting heinous immoral acts for the sake of things.
Changes in Alignment:
Alignment can change (gradually). A character can not change arbitrarily for instance from lawful good to neutral good simply to use a Fake ID. If a player says for instance, "My character is now chaotic good.", then they must ACT chaotic good. If a character acts chaotic good they are chaotic good if not they must change their alignment to fit their play. It takes roughly 10 hours of game play to change your alignment for example, from NG to LG.
NOTE: Lawful Good characters can not,I repeat, can not kill nor through inaction can they allow any humanoid to die, and yes, this includes their enemies. The only acception to this are undead and demons. If a Lawful Good character kills directly or indirectly they must change their alignment (even in an accedent). A Neutral Good or Chaotic Good character may kill but will get XP penalties for doing so.