All characters have the ability to hide, but this skill, Hide, improves the chance to hide by 20%. It may still require more than one attempt in order to hide successfully. It must be possible to hide in a location in order to get the bonus from this skill. Some locations may not allow hiding, and in such places even characters with this skill cannot hide.
When used successfully, the character will gain the Hidden Status Effect. Hidden characters are not invisible though, and can be found with a successful Search action. Certain skills, such as Enhanced Senses, will give the character with the skill the ability to see all hidden characters in their location. It will not show the hidden characters to anyone else.
Characters will lose their Hidden status if they perform an action that costs an Action Point, drop any item, speak, perform an emote, or promote a character in their faction. This simply removes the character from hiding and does not announce their presence to anyone in the room.
Hidden characters have a +5 damage bonus on their next (non-spell) attack against a character that is not aware of their presence. If the target can see the hidden character (for example, because the character has Enhanced Senses or because the character previously Searched and found them) there is no damage bonus applied to the attack. Regardless of whether or not the target is aware of the hidden character, the attack has a -20% to hit. Note that none of this is due to this skill, simply being Hidden provides said damage bonus and attack penalty.