The world of Pathfinder and of Pathfinder Society is a world called Golarion. The Age of Lost Omens below provides a basic introduction to the setting; you can learn more about Golarion from Chapter 8 of the Pathfinder Core Rulebook, from the Lost Omens line of setting books, and from the Pathfinder Wiki.
Ten thousand years ago, the world of Golarion came close to ending. Earthfall, as this extinction-level event came to be known, saw the world pummeled by a shower of falling stars that sank continents, hollowed out new seas, and destroyed civilizations. It took centuries for the world to recover, and centuries more for society to rebuild, but recover it did.
Dwarves ascended to the surface from the underground reaches of the Darklands in their legendary Quest for Sky, elves returned from the neighboring planet of Castrovel via a network of portals to reclaim their lands and traditions, and gnomes from the mysterious First World sought shelter from a now-forgotten terror. Survivors from other ancestries who had sheltered through the terror and destruction of Earthfall emerged during the Age of Darkness to reclaim their ancestral lands, from scrappy goblin tribes with a knack for surviving despite all odds against them to industrious halflings who emerged from the ruins to found societies of their own.
But humanity made the most astounding recovery. Less than 2,000 years after the near-extinction from Earthfall, the Age of Destiny saw the rise of many new human empires throughout the world. Humanity built wondrous structures, and its schools relearned magic that had been thought lost. Among these human nations walked a man named Aroden—an immortal survivor of the devastation of Earthfall. Aroden had long since cultivated a following of loyal subjects who regarded him with awe, for immortality was but one of the wonders he’d achieved. Greatest among these was his discovery of a shard of potent magic known today as the Starstone, a fragment from the stars that fell during Earthfall, which had lodged at the bottom of the Inner Sea. Contact with this alien artifact assailed Aroden with phantasmagoric visions, subjected him to a series of deadly martial trials, and posed exhausting moral quandaries that challenged his limits more than any of the arduous experiences he had yet endured. He emerged from this test a living god, and his first divine act was to raise the Starstone and the mass of land on which it had lain from the bottom of the sea to form the Isle of Kortos—also known as Starstone Isle—where he then established the city of Absalom.
In the centuries to follow, Absalom grew into one of the largest cities in the world, and Aroden’s legacy grew alongside it. As the millennia passed, his attentions increasingly turned away from the concerns of the Inner Sea’s inhabitants to otherworldly matters beyond mortal ken, but prophecy spoke of a time when he would return to Golarion and lead humanity triumphantly into an Age of Glory. As the time of Aroden’s return drew near, entire nations undertook monumental preparations to welcome him back to Golarion.
But instead, Aroden died, and with him the reliability of prophecy as well. Golarion was wracked by storms, war, and supernatural devastation as the god’s death marked the beginning of a new age—a time of uncertainty, but also a time of opportunity. This is the Age of Lost Omens, an age in need of heroes like never before.
—Pathfinder Core Rulebook 417
Your character is a member of an in-game organization known as the Pathfinder Society. Pathfinder agents are adventurers who travel throughout the world, exploring new places and chronicling both history and modern lore. The most significant and exciting Pathfinder missions earn a spot in the Pathfinder Chronicles, an ongoing series of journals that are copied and spread far and wide to share the Society’s discoveries with the world. Pathfinders agents come from all over the world and from all walks of life; anyone willing to work together with other agents to pursue the Society’s aims is welcome to try to join the organization. Together, these tenets are captured in the Pathfinder motto:
“Explore, report, cooperate.”
More information on the Pathfinder Society, and its role in Golarion can be found in Pathfinder Lost Omens: Pathfinder Society Guide. However some of the more relevant details are summarized below.
A rare few Pathfinders skip the usual training process, having already distinguished themselves in some way that proves that they have what it takes to be a Pathfinder. These agents receive field commissions, which allow them to engage in a far shorter training process. Field commissioned agents have fewer responsibilities back at the Grand Lodge, but they also tend to receive less material support from the Pathfinder Society than agents who built connections there during their years of practice and study.
Once an agent has completed their training, they have the freedom to travel the world and seek out places to explore.
Most Pathfinder missions are assigned by a group of leaders known as venture-captains. Venture-captains typically spend a lot less time in the field than adventuring agents, instead spending their time managing a lodge. In the process, venture-captains watch for leads for suitable missions, handle logistics and paperwork, and scout out nearby Pathfinders who might be interested in the adventure opportunities they have to offer.
At the top of the Pathfinder Society’s hierarchy are the Decemvirate, also known as the Ten. Most of the members of The Ten hide their identities behind magical masks, but recent rumors indicate that one of the Ten has decided to go public with her identity.
Factions have existed within the Pathfinder Society for centuries. However, their history is fraught with controversy, particularly when past factions clashed for control over the Society itself or acted as proxies for various nations’ political aspirations. Following more than a decade of turmoil, growth, and housecleaning, the Society’s current factions are dedicated to promoting different elements of the Pathfinder Society’s charter rather than pushing outside ambitions. Society agents understand that their allegiance is to the Pathfinder Society first.
The factions are divided into major factions and minor factions. A major faction ties very strongly and directly into the Society’s goals—such as emphasizing exploration or research—and has a large number of members within the Pathfinder Society. Minor Factions have a smaller profile, a more niche goal, have aims that are more tangential to the Society’s mission, or are tied to a shorter-term objective. Every season will have one or more Scenarios tied to a given major faction’s goals. Minor factions may also have scenarios tied to their goals, but it may not happen every season.
Envoy’s Alliance: Strength in Community
Envoys’ Alliance aims to bolster the Society’s ranks and represent its members, making the Society ever stronger, better trained, and better supported.
Grand Archive: Chronicling the Past
Archaeology is a destructive science, and adventurers tend to be more destructive than most. If the Society is to uphold its mandate to study and preserve the past, then documentation and academic rigor are key.
Horizon Hunters: Glory lies over the Horizon
The Horizon Hunters faction is home to those who carry on the proud tradition of ascending the highest peaks, plumbing the darkest depths, and seeing what lies over the next hill.
Vigilant Seal: Protect, Contain, Destroy
Members of the Vigilant Seal seek to ensure that ancient evils uncovered during their expeditions are properly dealt with—they protect ancient sites, contain possible threats, and destroy dangerous evils that can’t be safely contained.
Radiant Oath: A Light in the Shadows
Those who join the Radiant Oath swear simple vows to assist others, expanding on these promises the more they serve the faction.
Verdant Wheel: Truth Sprouts from the Ashes
Nature enthusiasts of all stripes—from grizzled trackers to bright-eyed ecologists to tenacious druids—gravitate to the Society for opportunities to witness natural wonders, catalog new species, and better protect the world’s pristine realms.