A Spell is the caster's stock-in-trade. Spells are magic incantations or powers conjured up by whatever game mechanism the developers allowed. Supposedly modeled after fantasy, myth and legend, spells do various kinds of damage. Spells are also used in many different ways depending upon which game one is playing. Very few games, if any, hold completely true to the fantasy-fiction concept of magic use.
See Spells for more details.