An Army Book in the Warhammer Fantasy tabletop wargame, is a rules supplement containing information concerning a particular army, environment, or worldwide campaign. Army Books for particular armies were introduced for the fourth edition of the game (prior to that all armies were included in the main rulebook). The sixth edition rendered these obsolete. Until superseded by newer versions, the 6th edition and later books remain valid for the newer editions of Warhammer.
Games Workshop has also released various expansions over the years, including a siege rules supplement and campaign expansions. Expansions and Supplements may or may not be valid over multiple editions, though generally they cycle similarly to the Army Books.
An Army Book normally contains:
Background - Information about the race and its place in the Warhammer world. This includes artwork, short stories, maps, timelines and copies of fictional documents.
Bestiary - A list of the units, characters and war machines that can be chosen for use in a battle. This includes their characteristic values, information on their weapon options, and any limitations on their use, as well as background information on each unit. An Army's special magic lore (if applicable) and special magic items are listed here.
Hobby section - Information on collecting, building and painting an army from the army book. This features outstanding example models painted by the Games Workshop 'Eavy Metal Team as well as Games Workshop's Army Painters and veteran hobbyists.
Army List - Each entry from the bestiary is arranged by type (Lord, Hero, Core, Special, Rare) and given a points value, with more powerful units costing more points, so that battles are fought between balanced armies. Options and costs are listed here.
Games Workshop and the Black Library (the Publishing arm of GW) have released Battlescrolls for Warhammer Fantasy. They are digitally released and expand the options available to players, as well as contain background on their subject. Most are formations that can be added to any army as a unit outside of the normal army organization. Some (noted below) are additions to specific army lists and are taken following the normal rules for their unit type.