Mysterious glowing shards that emit beams of light can be interacted with by player characters throughout Tamriel and the DLC zones of The Elder Scrolls Online. For every 3 Skyshards "collected", a character will earn one Skill Point and progression in the Skyshard Achievements page.
Collecting Lorebooks not only count towards Achievements but also towards the progression of your character's Mages Guild skill line.
Note that you don't have to go to EVERY Lorebook located as see on the maps below.
Each lorebook can be found within a cluster, area or in pairs of locations as indicated by the maps. Once you find one Lorebook, the other locations of the same Lorebook are gone and you can move onto the next cluster/general area of the next Lorebook you need!