From the Comprehensive Rules 4.0:
An artifact is a unique weapon, suit of armor, or other kind of special object used by a character.
Most artifacts tell you who their bearer can be. Other artifacts play to your support area.
Though artifacts are played and used much like possessions, they are a different card type. Artifacts are not affected by cards that affect possessions.
See also transfer.
Artifacts
Dwarven
Ring of Artifice
Ring of Guile
Elven
Galadriel's Silver Ewer
Narya, Ring of Fire
Nenya, Ring of Adamant
The Mirror of Galadriel, Dangerous Guide
Vilya, Ring of Air
Gandalf
Gandalf's Staff
Gandalf's Staff, Focus of Power
Radagast's Staff
Gondor
Anduril, Flame of the West
Crown of Gondor
Narsil, Forged by Telchar
Sapling of the White Tree
Seeing Stone of Minas Anor
The Shards of Narsil
Isengard
Saruman's Staff, Wizard's Device
The Palantir of Orthanc
Throne of Isengard
Moria
Whip of Many Thongs
Rohan
Throne of the Golden Hall
Sauron
Sceptre of the Dark Lord
Shire
Mithril-coat, Dwarf-mail
Wraith
Ring of Ire
Ring of Savagery
Cards That Support Artifacts
Dwarven
Thrarin, Smith of Erebor
Elven
Elrond, Elven Lord
Gandalf
Gandalf's Wisdom
Gollum
Gondor
Site
Shire
Frodo, Reluctant Adventurer
Cards That Counter Artifacts
Elven
Gandalf
Gollum
Orc
Uruk-Hai
card type table