Armor

Armour is a set of equipable defense items that reduce damage taken from enemies and most other damage sources. Armor pieces are equipped by placing them in the armor slots of the player's inventory. Armor can also be placed in vanity slots to change the player's appearance without affecting stats. Armor pieces are either crafted, purchased from NPCs, or dropped from enemies.

Each piece of armor has a defense statistic that reduces inflicted damage by half / /  its value, rounded up. For example, a full set of Copper armor provides a total of defense, reducing damage by  /  /  points. Silver armor grants a total of defense, reducing damage by  /  /  points, after having been rounded up. An attack cannot normally be reduced to zero; all attacks will always deal at least 1 damage (or 2 damage for a critical hit), regardless of the quality of a player's armor. The only times an attack can do 0 damage is if the player has invincibility for whatever reason or there is another player on the same team with the Paladin's Shield equipped and the attack does 1 damage normally.

In addition to the defense provided by individual armor pieces, most armor types provide a Set Bonus when all three pieces of the same armor type are worn simultaneously. For the basic pre-Hardmode ore armors (Copper through Platinum), this is an additional defense bonus. More advanced or unique armors can provide other specialized set bonuses (e.g., the Shroomite armor will provide invisibility when not moving).

Over all platforms, there are 34 different armor sets obtainable in pre-Hardmode; 35 different armor sets obtainable in Hardmode; 8 robes and 2 wizard hats that give additional buffs; and 10 miscellaneous armor pieces.

Wizard set
Though not a traditional armor set, these hats and robes confer a set bonus when worn together.

Miscellaneous armor
A few pieces of armor aren't part of any particular set.

Mixed armor sets
While set bonuses are a strong incentive to use a matched set, there are many cases where the powers of individual pieces can be combined usefully, especially late in the game. Particularly versatile pieces include the Valhalla Knight's Breastplate for its regeneration and the Forbidden Treads for the extra 2 minions (though the Forbidden Treads now provide only 1 extra minion in version 1.4, making them less ideal). Some examples include:
 * The Turtle chest piece can be combined with the Hallowed or Chlorophyte Mask and Hallowed Greaves for massively increased melee damage, but at the cost of losing the Thorns effect, a bit of defense, and most of the "enemy magnet" effect. With the Hallowed Mask, this nets a defense of 62 (against 65 for the full Turtle set), +18% melee damage,  +18% melee critical chance, and +10% melee speed.
 * With the Chlorophyte Mask instead, the defense goes up a point to 63 and the melee damage bonus rises to +28%, but the melee critical chance bonus drops to +14% and the melee speed bonus is lost. Either way, the wearer gets another +7% for all damage and +8% movement speed.
 * Doing this with the Valhalla Knight's Breastplate instead, gets another 3 points of defense, the regeneration, and a +30% bonus to summon damage, at the cost of some of the melee bonuses (leaving +10% or +20% damage, +10% or +6% critical chance).
 * The combination of the Chlorophyte Helmet and Shroomite Breastplate (or in the endgame, Vortex Breastplate) provides more ammo reduction than any set bonus. (See Sandgun for further discussion.)
 * A regenerative Melee/Summoner set consisting of the Chlorophyte Mask, Valhalla Knight's Breastplate, and Valhalla Knight's Greaves provides +16% melee damage, +26% melee critical strike chance, +30% movement speed, +50% minion damage, and +8 health/second regeneration.
 * For rangers, if the set bonus for Shroomite armor is not needed, the chest piece can be swapped with the Valhalla Knight's Breastplate for the regeneration. Those who use this approach may also wish to swap out the Shroomite Leggings for Forbidden Treads; the extra two minions (in versions earlier than 1.4) can provide a larger total DPS increase despite losing some movement speed and ranged critical bonus.
 * For magic users, Hallowed Headgear, Valhalla Knight's Breastplate, and Dark Artist's Leggings grants +100 mana capacity, +12% magic damage, +37% magic critical strike chance, +50% minion damage, and +8 health/second regeneration.
 * Summoners can summon their minions while wearing the Shinobi Infiltrator's Helmet, Valhalla Knight's Breastplate, and Red Riding Leggings for maximum damage bonuses, swap to the Spooky Helmet to summon one more, swap to the full Spooky Armor set to summon two more, before re-equipping the Forbidden Treads and Valhalla Knight's Breastplate (in that order). This grants high survivability while retaining decent minion damage/capacity bonuses, and is the strongest possible pre-Moon Lord summoning loadout that uses the Breastplate.