Silicon is typically a very poor conductor of electricity and often considered an insulator. However, a process called doping introduces a small amount of other material into the crystal structure to convert silicon from an insulator to a semiconductor. Semiconductors are essential parts of computers and other electronics.
Most metals are good electrical conductors, because the way in which their atoms connect allows electrons relatively free movement through the metal. However, silicon and other elements located near it on the periodic table of the elements form rigid crystalline structures that hold the electrons firmly in place. When scientists add a small amount of one of the neighboring elements to silicon, there is enough of a break in the rigid structure that electrons flow under certain conditions.
Diodes are the simplest of semiconductors. They allow electrons to flow, but in only one direction. One simple use of a diode is to protect an electronic device if the user inserts the batteries in the wrong direction. Transistors serve as switches and amplifiers for electrical current. Silicon chips hold thousands of transistors. Semiconductor chips greatly reduced the cost of electronics, such as computers, so they became affordable to the masses. The number of transistors on the chip allows reduction in size of computers and electronic devices.