Armor increases your character’s defenses, but some medium or heavy armor can hamper movement. If you want to increase your character’s defense beyond the protection your armor provides, they can use a shield. Armor protects your character only while they’re wearing it.
Your Armor Class (AC) measures how well you can defend against attacks. When a creature attacks you, your Armor Class is the DC for that attack roll.
Armor Class = 10 + Dexterity modifier (up to your armor’s Dex Cap) + proficiency bonus + armor’s item bonus to AC + other bonuses + penalties
Use your proficiency bonus for the category (light, medium, or heavy) or the specific type of armor you’re wearing. If you’re not wearing armor, use your proficiency in unarmored defense.
Getting in and out of armor is time consuming—so make sure you’re wearing it when you need it! Donning and removing armor are both activities involving many Interact actions. It takes 1 minute to don light armor, 5 minutes to don medium or heavy armor, and 1 minute to remove any armor.