Somatic component

The Somatic component is a basic part of spellcasting.

Many spells require the caster to make a motion to cast the spell. If the caster is unable to make the correct motion, the spell cannot be cast. Wearing armor or using a shield interferes with the somatic components of arcane spells, creating a risk of spell failure. Bards and some other arcane classes can cast spells in light armor without this risk.

Each spellcasting tradition has it's own somatic component.