Few warriors venture onto the battlefield without some measure of protection, be it only a padded leather jerkin or a gleaming suit of plate mail. Many creatures shun conventional armour, protected instead by their own thickened skin or scaly hides.
Whatever the case, the level of protection given is represented by the Armour Save roll – a test made against a model's armour value – the more armour a model wears, the better its armour value becomes and the more likely it is to successfully pass an Armour Save roll.