This chapter traces the history of steelmaking over three millennia, from the discovery of martensite in a mining tool dating from the twelfth century B.C. to the nineteenth century development of the Bessemer and Siemens processes. It also describes the work of early metallographers who discovered many phases and microstructures associated with steel and gave them their now familiar names. The chapter concludes with a brief discussion on the emergence of continuous casting and the subsequent development of strip casting production techniques.