The development of biosensors is a fascinating journey that combines advances in chemistry, biology, and engineering. This chapter traces the key milestones and technological breakthroughs that have shaped the evolution of biosensors from their inception to the sophisticated devices we use today. Electrochemical biosensors represent a vital intersection of chemistry, biology, and electronics, offering robust solutions for detecting a wide range of analytes. This chapter aims to introduce the basic concepts, historical development, and current significance of electrochemical biosensors. By providing a foundational understanding, it sets the stage for exploring more specialized topics in subsequent chapters.