The abundance discrepancy in H II regions

In this paper we discuss some results concerning the abundance discrepancy problem in the context of H II regions. We discuss the behavior of the abundance discrepancy factor (ADF) for different objects and ions. There are evidences that stellar abundances seem to agree better with the nebular ones derived from recombination lines in high-metallicity environments and from collisionally excited lines in the low-metallicity regime. Recent data point out that the ADF seems to be correlated with the metallicity and the electron temperature of the objects. These results open new ways for investigating the origin of the abundance discrepancy problem in H II regions and in ionized nebulae in general.