Succeeding in battle takes more than just a good weapon. It also requires that you have the right outfit to defend yourself properly from the attacks of your enemy. Armor is divided into different types such as cloth, leather, plate and more.
Here is some of the armor types explained:
Cloth armor

This material provides the least amount of defense, but allows the wearer more freedom of movement. Mostly used by casters and in various types of social clothing.
Light armor

This is used to categorize armor types such as leather and hide which is stronger than cloth, but still fairly weak. Some casters can use this, and most if not all melee-oriented characters.
Medium armor

This is used to categorize armor types such as chainmail and splintmail. Considerably stronger than the armor types above and mostly reserved for melee-oriented characters.
Heavy armor

This is used to categorize armor types such as halfplate and fullplate. This is some of the strongest armor you can find, and it can only be used by skilled melee-oriented characters.
Shields armor

Some character classes can equip a shield to aid them in battle. Shields can be heavy and hard to manage, so only the most able fighters are able to use them when fighting enemies.
Source: AoC Official Site