In Path of Exile 2, support gems are special skill gems that modify the behavior of active skills when linked together in a socketed item. Unlike regular skill gems that let you cast spells or attack, support gems enhance those abilities by adding effects like extra damage, faster casting, or additional projectiles.
While some players wrongfully assume they can just use any support gem they want, that isn’t the case. Every support gem must be linked to an active gem to be used. That too in the same gear, making things a little more technical and requiring players to put in thoughts to maximize their build’s efficiency.