Some spells have a specific target or targets. A caster uses these spells directly on creatures or objects, as defined by the spell itself. The caster must be able to see or touch the target, and must specifically choose that target. The caster does not have to select his or her target until he or she finishes casting the spell.
If the character casts a targeted spell on the wrong sort of target the spell has no effect.
Subject: The descriptive text of spells makes a distinction between “target” and “subject.” The target of a spell is the creature(s) or object(s) it is directed against. A target becomes a subject if it fails a saving throw against the spell and is thus affected by the magic.