A cantrip is the name given to any spell of the lowest level that an arcane caster, such as wizard or sorcerer, might cast. The magic associated with a cantrip is so inconsequential that a spellcaster might cast it without limit. Nevertheless, wizards must still write cantrips in spellbooks in order to memorize it for casting.
Some cantrips are classified as rare cantrips and spellcasters that usually gain access to all cantrips do not automatically gain access to such spells when they start their arcane careers. A spellcaster gains access to rare cantrips only by uncovering their secrets in some other way. Some are guarded by jealous mages, while others are lost in missing libraries or moulder on forgotten scrolls.