The components of a spell represent what is required of a caster for the actual casting of that spell, in addition to having the spell available (c.f. spell slot). There are two types of components in Neverwinter Nights — somatic, representing gestures, and verbal, representing speech. These components are kept abstract in the sense that particular words and gestures are not described for each spell. Instead, just the type(s) of required components are listed for each spell (sometimes abbreviated "S" and "V"), allowing players to fill in the details with their imaginations. (Dungeons & Dragons included a third type of component — material, representing various powders and reagents consumed by casting a spell — but this is only implemented in Neverwinter Nights as custom content.)
A somatic (S) component is a measured and precise movement of the hand. An arcane spellcaster wearing armor or using a shield incurs a chance of spell failure (the amount is noted in the armor or shield description) when casting any spell with a somatic component. The casting of nonsomatic spells is not subject to spell failure due to armor and shield. (In Dungeons & Dragons, a somatic component also required having a free hand; this was not implemented in Neverwinter Nights.)
A verbal (V) component is a spoken incantation, which must be uttered with a strong voice. A silence effect spoils the incantation, hence no spells with a verbal component may be cast while silenced. A spellcaster who has been deafened has a 20% chance of failure when casting an arcane spell with a verbal component. The casting of nonverbal spells is affected by neither silence nor deafness.