"FNAF" refers to the "Five Nights at Freddy's" game series, created by Scott Cawthon. It is a popular horror franchise known for its unique and intricate lore.

The story of "FNAF" revolves around a chain of fictional family entertainment restaurants called Freddy Fazbear's Pizza. The main character, usually a night security guard, is tasked with monitoring the animatronic characters throughout the night.

However, it is revealed that these animatronics possess a dark secret. They are haunted by the spirits of children who were killed in the pizzeria by a murderer named William Afton, who dons the identity of "Purple Guy." The animatronics come to life at night and roam the restaurant, seeking revenge on anyone they encounter.

Throughout the series, players uncover the disturbing history of the pizzeria, the animatronics, and the tragic events that took place. The lore expands through a combination of in-game clues, mini-games, hidden easter eggs, and supplementary material.

As the games progress, new characters are introduced, including additional animatronics and an enigmatic animatronic known as "Golden Freddy." The story delves into themes of tragedy, loss, and the consequences of human actions.

The "FNAF" lore has been expanded through numerous sequels, spin-offs, novels, and even a film adaptation. It has garnered a dedicated fan base that enjoys unraveling the mysteries and piecing together the intricate puzzle of the franchise's narrative.