Some feats have prerequisites. Your character must have the indicated ability score, class feature, feat, skill, base attack bonus, or other quality designated in order to select or use that feat. A character can gain a feat at the same level at which he gains the prerequisite.
A character can't use a feat if he loses a prerequisite, but he does not lose the feat itself. If, at a later time, he regains the lost prerequisite, he immediately regains full use of the feat that prerequisite enables.
Some feats are general, meaning that no special rules govern them as a group. Others are item creation feats, which allow characters to create magic items of all sorts. A metamagic feat lets a spellcaster prepare and cast a spell with greater effect, albeit as if the spell were of a higher spell level than it actually is.
Feats are summarized on Table: Feats below. Note that the prerequisites and benefits of the feats on this table are abbreviated for ease of reference. See the feats description for full details.
The following format is used for all feat descriptions.
Feat Name: The feat's name also indicates what subcategory, if any, the feat belongs to, and is followed by a basic description of what the feat does.
Prerequisite: A minimum ability score, another feat or feats, a minimum base attack bonus, a minimum number of ranks in one or more skills, or anything else required in order to take the feat. This entry is absent if a feat has no prerequisite. A feat may have more than one prerequisite.
Benefit: What the feat enables the character (“you” in the feat description) to do. If a character has the same feat more than once, its benefits do not stack unless indicated otherwise in the description.
Normal: What a character who does not have this feat is limited to or restricted from doing. If not having the feat causes no particular drawback, this entry is absent.
Special: Additional unusual facts about the feat.
Feats that grant extra uses of class abilities, like Extra Channel or Extra Rage, effectively grant the affected ability a pool of additional uses each day. If you have levels in multiple classes that have the same ability (or abilities that are considered as others for feat purposes, like the skald's raging song counting as bardic performance), this single pool applies to all those abilities together, and doesn't grant extra uses to each one separately. You may spend this pool of uses each day on any of these abilities in whatever manner you choose.
For example, if you have levels in both barbarian and bloodrager and you take the Extra Rage feat, you gain 6 extra rounds that you can either use to rage or bloodrage or split between the two. The feat does not give both an extra 6 rounds of rage and 6 rounds of bloodrage—it gives you exactly 6 rounds each day that you can use for either one of these abilities. One day, you might use 4 of these rounds for rage and 2 on bloodrage; the next day, you might use 3 on each.