Lore are the various pieces of information about the story, places, characters, and history of the world of May'Eyal.
Lore frequently appears as scroll-like items, and is most commonly found lying on the ground, inside stores, on the bodies of NPCs, or by touching signposts, murals, or statues. Some lore is also unlocked by completing quests, finding or equipping items, or using items at specific locations. Not all races and classes are able to access all areas containing lore, and some lore is only available to classes that know Trapping (category).
The Sher'Tul Fortress has a library of all lore you've unlocked, except for item descriptions, which must be unlocked each playthrough.
A spreadsheet of how to unlock lore is available here. Items marked in red have not yet been confirmed. (See the discussion page for more information.)