A microprocessor is a tiny but incredibly powerful computer chip that acts as the brain of electronic devices. Inside your computer, tablet, or phone, a microprocessor follows billions of instructions every second, doing everything from displaying words on the screen to running games to connecting you to the internet.

Before microprocessors, computers were enormous machines that filled entire rooms and cost millions of dollars. The invention of the microprocessor in 1971 changed everything. Engineers figured out how to etch thousands (now billions) of microscopic electronic circuits onto a chip smaller than your fingernail. These circuits work together to perform calculations, make decisions, and control other parts of the device.

Think of a microprocessor like an incredibly fast worker who can read instructions and carry them out. When you press a key on your keyboard, the microprocessor receives that signal, figures out what letter you pressed, tells the screen to display it, and helps the device decide what to do next. All this happens faster than you can blink.

Modern microprocessors contain billions of tiny switches called transistors that turn on and off millions of times per second. The more transistors a microprocessor has, and the faster it can switch them, the more powerful it becomes. Today's smartphones have microprocessors more powerful than the computers that helped send astronauts to the Moon.