Since the discovery of high temperature superconductivity in the iron pnictide/ chalcogenide materials, at least there are seven related structural types have been fabricated. In the 1111 system, the highest superconducting transition temperature (Tc) measured by resistivity and magnetization can reach 56 K. There are some hints that the Tc can be increased to higher values. The iron based superconductors have multiband feature. Many unconventional electronic properties in the normal state of iron based superconductors have been discovered. The iron based superconductors have relatively longer coherence length, more three dimensional electronic property, higher upper critical field and irreversibility field, very strong flux pinning, therefore they have the great potential for applications for producing high magnetic field. In this short overview, we will give a brief survey about the development of materials and physics of iron based superconductors. We give detailed descriptions on the properties for several kinds of materials with the major structures. In addition, we will give a introduction about the present understanding of the pairing mechanism. Finally we will try to give a perspective on the potential applications of the iron based superconductors.