Game Mechanics
Master guide to POE2's elemental and status effect mechanics
Categories
Items come in Normal, Magic, Rare and Unique rarities, each with different modifier potential. Item level controls which modifiers can appear.
Armour and weapons can have rune sockets; runes add fixed stats such as resistances or maximum life. Skill and support gems are socketed into your skills (not your gear) - supports link to a skill via support sockets added with Jeweller's Orbs (up to 5).
Use currency orbs to craft: Transmutation/Augmentation for Magic, Alchemy/Regal for Rares, Exalted to add mods, Divine to reroll values, and Chaos to swap one mod for another.
Deterministic options include Essences (add a specific mod by tier), Alloys (guaranteed exclusive mods, 0.5.0), and Desecration/Bones crafting from Abyss.
Fracturing Orbs lock a desirable mod in place, and Runeforging with Verisium can add Runic Ward to armour.