| − | A '''field''' is a commutative [[Ring (mathematics)|ring]] which contains a non-zero multiplicative identity and all non-zero elements have multiplicative inverses. Everyday examples of fields include the [[real numbers|real numbers]], [[complex numbers]] and the [[rationals]]. Besides the trivial field, the set of rationals is the smallest number field, so any other number field is an extension field of the rationals. | + | A '''field''' is a commutative [[Ring (mathematics)|ring]] which contains a non-zero multiplicative identity and all non-zero elements have multiplicative inverses. Everyday examples of fields include the [[real numbers|real numbers]], [[complex numbers]] and the [[rationals]]. There is a finite field for each power of a prime number. |