In this paper we characterize a
new set of prime ideals of an integral domain D, called the set of F-primes of D, that
we show to have the following properties: (1) D is the intersection of all DP where P
is an F-prime of D;(2) all principal prime ideals and all essential prime ideals (those
prime ideals for which DP is a valuation domain) are F-primes; (3) if D is a
GCD-domain, then the F-primes of D are precisely the essential primes of D; (4) D
is a UFD if and only if the set of F-primes is precisely the set of principal prime
ideals of D.