Editing 4SRD:Basics (section)

==SURPRISE==
When a combat starts, if you are not aware of your opponents and they are aware of you, you are surprised.<br>

Determining Awareness<br>
Sometimes all the combatants on a side are aware of their opponents, sometimes none are, and sometimes only some of them are. Sometimes a few combatants on each side are aware and the other combatants on each side are unaware.<br>
Determining awareness may call for Perception checks or other checks.<br>
The Surprise Round: If no one or everyone is surprised, no surprise round occurs.<br>
If some but not all of the combatants are aware of their opponents, a surprise round happens before regular rounds begin. Any combatants aware of the opponents can act in the surprise round, so they roll for initiative. In initiative order (highest to lowest), combatants who started the battle aware of their opponents each take a standard action during the surprise round. You can also take free actions during the surprise round. You cannot spend an action point.* <br>
Surprised Combatants: Combatants who are unaware at the start of battle do not get any actions in the surprise round, not even free actions. Unaware combatants grant combat advantage.*<br>