Manual

Interface
Understanding Your Target
As you adventure in World of Warcraft, you will encounter more than just
friendly NPCs and simple beasts. You will meet many creatures and
characters, and you will need to understand how to interpret the
information you get when viewing them.
FRIENDLY PLAYERS
Other friendly players appear with blue names over their heads,
whether you have them selected or not. If they belong to a guild, their
guild name will appear under their name. When you mouse over or
select a friendly player, its tool tip will also appear blue.
OPPOSING PLAYERS
By default, all player characters have blue names. However, if a player
turns on the player versus player flag and indicates that he or she wants
to fight other players, then that player's name and tool tip turn red,
indicating that they are hostile.
NON-PLAYER CHARACTERS (NPCS)
NPCs are any humanoid character you can interact with, such as
merchants, aerial mount masters, and quest givers. Their names only
appear over their heads when you click on them. The tool tips of
friendly NPCs are green. The tool tips of enemy faction NPCs are red.
MONSTERS
Monsters are any characters that are not also faction's NPCs and that
will fight back if you attack them. There are two categories of monsters:
passive and aggressive. Passive monsters have yellow names and tool
tips and only fight if struck first. Aggressive monsters have red names
and tool tips, and attack you on sight. Some monsters are also social,
and will call for help from others if they are in combat.
CRITTERS
Critters are non-combative animals, such as sheep, rabbits, cows, and
prairie dogs. These animals will never fight you, even if you attack
them. Killing a critter earns you no experience.
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