Stealthing
Stealthing is the art of disappearing without a trace, and making sure that nobody will find you afterwards
Hiding
A character can attempt to hide at his current location, given that he is at least slightly obscured. Attempting to hide requires a Stealth-check, which will be challenged by an Perception-check by every creature that has currently line of sight to the character.
If the character is slightly obscured, the checks will be compared at face value, and if the hiding character beats every single opposing Perception-check, he will be considered hidden.
If the character is completely obscured, the Perception-checks will suffer a -8 penalty.
If the character is not obscured at all, the Stealth-check will suffer a -20 penalty.
At the beginning of each turn, a character can make a new Perception check to see if he can locate the hidden character. The Stealth-check result from when the character started hiding will be used for each of those new Perception-checks.
Characters may investigate the last known location of where the character was hiding, and may head to that location. If they walk within 3 meters of the character and have line of sight, he will be automatically revealed.
Obscurity
Depending on how well the character is currently visible in the world, he has different levels of obscurity, which may make it harder or easier to hide.
Not Obscured
The character is standing in a well lit room, or outside during the day, with no cover at all. In order to hide from this position it would require truly blind foes.
Slightly Obscured
The character is in a dim lit area, like candle light or a shady ally during the day. Alternatively he has some slight coverage from trees, crates or other objects lying around.
Completely Obscured
The character is either in complete darkness, or completely covered by objects. Keep in mind that the complete darkness does not work against character with Darkvision or, versus spellcasters, characters with Magic Vision.