Abstract: This paper begins with a classical definition of hypersonic, some physicalphenomena pertinent to hypersonic flight, the covered range of the hypersonic flight and the features of design process. The differences betweenAHV(hypersonic airbreathing vehicles) and RHV(hypersonic rocketvehicles) are discussed, with a table showing temperatures. In thesecond part, the paper puts hypersonic vehicles in a militarybackground. A historical perspective of hypersonic vehicles is given inform of a table with milestones, accompanied with some lessons learnedfrom the past and relevant for the future. In the last part, a typical design process, development strategy,technology program, and key technologies of hypersonic airbreathing vehiclesare reviewed.