Your action points, sometimes called AP (and referred to as ‘Actions’ in your score) are an abstract way of reflecting how fast you can fight. Each second you gain a number of action points equal to your Speed, although this cannot exceed your speed cap. You then spend these action points to perform various combat techniques, eat food, rewield disarmed weapons, and so on.
Your maximum action points are 800, plus 20 for each point of Speed. Your true Speed stat (before the cap) is used when calculating this maximum.
If you enter a rage (for example via Berserker Rage, or a class power) and your maximum number of action points increases, your current action points will also increase by the same amount. These extra action points will vanish when the rage ends, unless doing so would take you below 0.
If your action points fall below 0, you become fatigued (see ‘help fatigue’).
See also: speed combat eat wield