Gem tag

All skill gems have gem tags (also called keywords) listed in the first line of the mouseover description. They are used for dividing the skills into groups and to clarify which type a skill is. They do not indicate which modifier (or stats) apply to a skill however.

Mechanics
Gem tags only categorize skills into groups, so effects like can apply to them.

In particular, there are common misconceptions about gem tags:
 * gem tags are only granted by skill gems, skills granted from items or threshold jewels do not modify gem tags in any way
 * they do not describe which gems can support other gems and are not meant to, even if it often does line up
 * they do not describe which stats (and to that extend modifiers) apply to a skill