Equipment can have up to six sockets, which are used to slot skill gems. Sockets can be linked together, allowing support gems to affect skill gems. Sockets also have colours (Red for Strength, Green for Dexterity, Blue for Intelligence), which must match the gem's colour. You use Chromatic Orbs to change colours, Jeweller's Orbs for sockets, and Orb of Fusing for links. Crafting good socket/link/colour combinations is crucial.
