What are prestige points? Well in short, they are acquired points that your PC’s can spend for a variety of purposes to gain abilities that affect game play. Some of these effects are temporary in duration, such as Round and Encounter Abilities, while other abilities are Permanent in effect.

How do you gain prestige points? Simple. By assisting in the creation of the Planescape campaign site. Exactly what this contribution consists in will vary.
However a typical way of earning points is to keep an updated character journal.

Once points have been acquired, they may be used in one of three ways. First, they may be used once per combat round to gain a short term benefit lasting the duration of that round (refer to the Round Abilities table below). Each Round Ability uses up 1 prestige point. You may use only one of these abilities per round, however you may choose to double the numeric effect of any given ability by using an additional 2 prestige points . Points “used” in this way are not permanently lost but refresh at the start of the next game session.

Second, prestige points may be used once per combat encounter to gain an immediate short term benefit (refer to the Encounter Abilities table below). Each Encounter Ability uses up 2 prestige points. While you may only “use” prestige points to gain Encounter Abilities once per encounter, you may also choose to “burn” prestige points to gain additional Encounter Abilities. Each additional Encounter Ability gained in this way burns 1 prestige point. Points “burned” in this way are permanently lost.

Finally, prestige points may be burned either during a game session, or out of session, to gain some permanent benefit. The burn cost of these abilities varies (refer to the Permanent Abilities table below), but regardless of cost, no single ability may be purchased more than twice by the same character.