With a higher transition temperature (T_c), the recent discovery of iron-based superconductors has evoked eagerness for extensive research on these materials because they form the second high-temperature superconductor family after the copper oxide superconductors and impart an expectation for materials. Including an unconventional pairing mechanism and superconducting properties preferable for application such as a high upper critical field and small anisotropy, they have peculiar physical properties. The new star in the world of solid state physics are iron-based superconductors. Due to the discovery of superconductivity in iron-based materials, it has exposed a new family of high-temperature superconductors with properties that are both similar to and different than those of the copper-oxide family of superconductors. These materials promise to provide a rich playground to study the fundamentals of superconductivity with transition temperatures approaching the boiling point of liquid nitrogen, while advancing the prospects for widespread technological applications. In this paper, we review the properties and applications of iron-based superconductors. The advantages and disadvantages of iron-based superconductors over high T_c superconductors and cuprate-based superconductors have been also studied.