Electronics refers to devices and systems that use electrical circuits to control the flow of electricity in useful ways. Unlike simple electrical devices that just turn power on and off (like a basic light switch), electronics manipulate electricity precisely to do complex tasks.

Your computer, smartphone, and calculator are all electronic devices. They contain tiny components called transistors that act like microscopic switches, turning on and off millions of times per second to process information, display images, play sounds, and connect to the internet. A television uses electronics to transform broadcast signals into the pictures and sounds you see and hear. A video game console uses electronics to create entire virtual worlds.

The field of electronics emerged in the early 1900s with the invention of the vacuum tube, but it exploded in the 1950s when scientists invented the transistor. Today's smartphones contain billions of transistors, each smaller than a speck of dust, working together to give you more computing power than the massive room-sized computers of the 1960s.

Electronics transformed modern life. They enable everything from medical devices that monitor your heartbeat to spacecraft exploring distant planets. The word can also refer to the scientific study of how to design and build these devices: an engineer might major in electronics in college, learning to create the circuits behind tomorrow's inventions.