Integrated Circuits are found in every conceivable electronic device, and control the on-off behavior of a device capable of conductive behavior. They evolved from vacuum tubes and transistors to incorporate hundreds of thousands of transistors on a single chip today.
IC's and semiconductors now control computing, communications, networking, and other facets of daily modern life. They are created by "etching" a pattern onto a semiconductor platform, such as silicon, which can then be controlled by exposure to electrical current.
Semiconductors are the individual "on-off" switches that make up a electronic devices. By only allowing the conductance of electricity in specific situations (as opposed to conductors and insulators), semiconductors can produce complex and sophisticated behaviors, calculations, and measurements. By working in tandem, many semiconductors can constitute an mp3 player, computer processor, or wireless network adapter.