Stack

Stacking is the concept where more than one instance of the same type of effect is accumulative. The rules which determine if something can stack or not is very unclear, and there are many exceptions to the rules. Most of these take into consideration where the effect comes from (ie gaining a Dodge bonus from a feat will stack with one from an item, but you cannot stack 2 from different items).

Examples of things which DO stack:
 * Items with bonuses to your Ability Scores will continue to stack until you reach +12
 * Items with a Dodge bonus will stack with feats that also provide this bonus

Examples of things wich DO NOT stack:
 * Items with the same bonus to your AC such as a Ring of Protection and a Cloak of Protection
 * Multiple uses of spells such as Bull's Strength (spell)