The Pathfinder Society is a globe-spanning organization based out of Absalom, the world’s largest city. The membership consists primarily of Pathfinders, adventurers who travel throughout Golarion, usually inconspicuously, and explore, delve, and otherwise experience the lesser-seen parts of the world. They send journals back to their venture-captain, who also assigns them new missions and suggests new places to explore. The most exciting and illuminating of these journals are compiled in the Pathfinder Chronicles, an ongoing series of books which collect the history and mystery of Golarion for their membership.
The day to day running of the Pathfinder Society is managed by the venture-captains. These are usually older or accomplished Pathfinders, or long-time allies of the organization, who have settled down, and claimed a Pathfinder lodge for themselves. They direct Pathfinders in the field towards new and interesting locales, and receive the regular reports that will eventually become part of the Chronicles.
They receive their instruction from the Decemvirate, a secret body of ten masked individuals who pass messages along to the captains in subtle and silent ways. Little is known about the Decemvirate, not even their ultimate goals for the collection of the endless data the Society receives.
Members of the Socitey are loosely affiliated adventurers, who are not required to interact. However, they are forbidden direct conflict against each other, but this doesn’t stop the more unscrupulous from leading rival parties into dangerous situations and dead ends. Most are issued a Wayfinder , which is a type of magical compass, and taught to recognize the signs indicating a lodge. Other than that they are largely free to be and do what they please. This allows for a very varied membership, with a Chelaxian devil-binder and a Garundi rogue easily finding themselves sharing a night in the same lodge in the far north of Avistan.
All information has been lifted from the Pathfinder Wiki at http://pathfinder.wikia.com/