The Four Symbols Seal is an integral part of Uzumaki fūinjutsu. It can be used for many different purposes, up to the point of sealing tailed beasts. Its other uses include sealing away chakra, people or objects, or even souls. It requires a great deal of fūinjutsu skill and is mainly used to seal large amounts of chakra or giant enemies. It is also referenced that it could be 'encoded' to a certain person's chakra, so it will only open for them.