This review summarizes the experimental and theoretical studies on the electronic, magnetic, and structural properties of Fe-based superconductors, particularly those with FeAs layers. The discovery of superconductivity in LaFeAsO$_{1-x}$F$_x$ in 2008 at $ T_c = 26~K $ sparked extensive research, leading to the identification of various Fe-based superconductors with $ T_c $ up to 56 K. The review focuses on the 11-, 122-, and 1111-type FeAs-based compounds, which have been the most extensively studied. These materials exhibit a layered structure with FeAs layers separated by spacer layers, and their superconductivity is believed to be associated with the Fe square lattice layers. The review discusses the structural properties, including the relationship between the Pn-T-Pn bond angle and $ T_c $, the Pnictogen height and $ T_c $, and the orthorhombic distortion and superconductivity. It also covers the normal-state properties, such as electronic and magnetic properties, and the superconducting properties, including the superconducting energy gaps, spin of a Cooper pair, and the superconducting mechanism. The review highlights the importance of understanding the electronic and magnetic mechanisms underlying superconductivity in these materials. The phase diagrams of various Fe-based superconductors are discussed, showing the relationship between composition, temperature, and superconducting properties. The review also addresses the role of doping, pressure, and structural distortions in influencing $ T_c $. The study of these materials has led to insights into the potential for high-temperature superconductivity and its possible applications. The review concludes with a discussion of the current understanding of the superconducting mechanism and the remaining scientific questions that need to be addressed.This review summarizes the experimental and theoretical studies on the electronic, magnetic, and structural properties of Fe-based superconductors, particularly those with FeAs layers. The discovery of superconductivity in LaFeAsO$_{1-x}$F$_x$ in 2008 at $ T_c = 26~K $ sparked extensive research, leading to the identification of various Fe-based superconductors with $ T_c $ up to 56 K. The review focuses on the 11-, 122-, and 1111-type FeAs-based compounds, which have been the most extensively studied. These materials exhibit a layered structure with FeAs layers separated by spacer layers, and their superconductivity is believed to be associated with the Fe square lattice layers. The review discusses the structural properties, including the relationship between the Pn-T-Pn bond angle and $ T_c $, the Pnictogen height and $ T_c $, and the orthorhombic distortion and superconductivity. It also covers the normal-state properties, such as electronic and magnetic properties, and the superconducting properties, including the superconducting energy gaps, spin of a Cooper pair, and the superconducting mechanism. The review highlights the importance of understanding the electronic and magnetic mechanisms underlying superconductivity in these materials. The phase diagrams of various Fe-based superconductors are discussed, showing the relationship between composition, temperature, and superconducting properties. The review also addresses the role of doping, pressure, and structural distortions in influencing $ T_c $. The study of these materials has led to insights into the potential for high-temperature superconductivity and its possible applications. The review concludes with a discussion of the current understanding of the superconducting mechanism and the remaining scientific questions that need to be addressed.