Abstract
The study of the Extremly Red Objects (EROs), is the importance for setting constraints on the first epoch of massive galaxy formation, for exploring the population of dust reddened starburst and for testing models of galaxy formation in general. They are defined as objects with I-K>4(Vega). The traditional picture identifies the EROs either with passively evolving elliptical galaxies, or with young starburst reddened dust.
