Iron, being one of the most abundant elements in Earth with a suitable density, is recognized as the principal component of the core. There is intensified interest in study of iron at physical conditions of the core because of new developments in high pressure-temperature theoretical techniques. Iron occurs in four distinct polymorphs. Three (BCC body centered cubic, δ-BCC and FCC) are stable at one atmosphere and the fourth (HCP) phase at high pressures. We have combined all the available experimental and theoretical data to obtain a phase diagram of iron at core conditions.