Semiconductors are materials characterized by an electrical conductivity value between that of an insulator and a conductor. Their defining property is the ability to have this conductivity precisely altered through processes such as doping, which involves introducing controlled amounts of impurity atoms into the crystal lattice. This inherent tunability allows semiconductors to form the fundamental components of modern electronics, including transistors and diodes. These devices operate by controlling the flow of electrical current, enabling complex switching and signal processing critical to computing, communication, and power systems.