Inspired by D&D 3.5e, pathfinder is very similar to D&D but deeper and heavier, giving players more options when building and growing their characters. It also expands and changes many mechanics to offer a more complex and interesting system. If you like D&D but want more from your games, pathfinder is definitely worth a read.
What the Library has:
Core Rulebook - The Core Game in 1 book, contains all the necessary rules to play
Bonus Bestiary - More monsters and foes for a GM to use on their players
Pathfinder Module: Master of the Fallen Fortress - An adventure for beginners focused on exploring an ancient, ruined tower.
Pathfinder Module: Dawn of the Scarlet Sun - Solve a set of gruesome killings and face dangerous foes in a bustling fantasy city
Ultimate Combat - Bonus classes and features focusing on martial prowess and combat in general
Core Rulebook - All the rules needed to play the updated version of pathfinder, more focused and streamlined
Playtest - The original playtest version of the rules, useful for reference