Typically used with: Presence.
In short: present. All the world's a stage and you're the star — or so your prima donna attitude would suggest. Characters with ranks in Perform are "the talent," and are superbly good at entertaining others. Such a trade can be used to lighten moods and create diversions.
When you buy a rank in Perform, your character also gets the added bonus of learning a new performing art (e.g. tuba, dance, singing, mimicry, coitus, comedy). Ask your GM if a particular performing art is applicable in your campaign. Usually, you'll need to be trained in an art of performing if you want to make effective use of it for the purposes described below — it's hard to move hearts when you stink at the clarinet. Ranks in an Occupation specific to a means of performing (e.g. violinist, comedian, actor) are always applicable to Perform rolls involving that talent, and obviate the need to buy a rank in Perform to learn the talent.
If you want to impress your audiences, move them to tears, and incite a standing ovation, you're the headliner so you'd better nail it. Make a Perform check. The higher the result, the better your performance. Anything lower than a result of 15 is considered amateur hour. A result of 20 is notable and enjoyable. A result of 25 is absolutely stellar and memorable. A result of 30 is legendary and guarantees your spot in the minstrel hall of fame.
If you're performing in a group (e.g. a band, a symphony orchestra, the cast of a play), everyone has to make Perform checks. You can take the average to determine the quality of the performance. Even though a player with a high roll may stand out (e.g. with a guitar solo or a monologue in the spotlight), the entire production suffers because of those with low rolls.
You can't retry Perform checks unless you want to do the act over again, and no audience would stay for a rerun after they've exhausted their supply of tomatoes to throw. Especially high Perform checks, on the other hand, will attract all kinds of attention from the upper echelons of society, both good (an invitation to play for the emperor) and bad (a record deal).
You can make a Perform check to build a relationship with a creature and improve its Disposition toward you. Essentially, your performance impresses them enough to fall in love with your talent. To gain a groupie, roll a Perform check opposed by the creature's Discern check. If your result is higher, you may improve their Disposition. For each 5 points of difference, you improve the creature's Disposition by one level. If your check is a Critical Failure, you actually worsen their Disposition by one level.
You can only attempt this once per day per creature. Each attempt generally takes a few minutes. You may attempt to befriend any creature of an elemental, humanoid, or legendary Nature. You may also attempt to befriend any fabricated, plantlike, or undead creature with an Intellect higher than 1.
With a high enough Perform check, you can capture the gaze of others and keep them fixated on you. Roll a Perform check opposed by their Mind Control check. If your result is higher, you mesmerize them and they gain the distracted condition. If your opponent rolls a Critical Failure, they gain the wide-eyed condition against anyone but you.
The effects of your performance can last up to 10 minutes, but you must perform the whole time. If your performance ceases or something else catches the opponent's attention, the effect ends. You may attempt to enthrall the same types of creatures as listed in the "Befriending" section.