What is a CPU?
The short answer
A CPU is the part of a computer that follows a program's instructions, one tiny step at a time, billions of times every second.
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A small chip inside every computer
Open a laptop or a phone and you find a flat square chip, a few centimeters across. That chip is the CPU.
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It follows a recipe, one step at a time
A program is a list of tiny steps, called instructions, like a recipe. The CPU reads a step, does it, then reads the next one.
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Billions of steps every second
A clock inside the chip ticks very fast, and the CPU's work moves forward on every tick. 3 GHz means 3 billion ticks a second.
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Many cooks in one chip
Today's CPUs hold several cores. Each core is a cook of its own, so eight cores can work on eight jobs at once.
4 words
Words to know
- Program
- A list of steps for a computer to follow.
- Instruction
- One tiny step in a program, such as “add these two numbers”.
- Clock speed (GHz)
- How many times a second the CPU's clock ticks. 1 GHz is one billion ticks a second.
- Core
- One complete worker inside a CPU. More cores can do more jobs at once.
At work
Where you meet it at work
Chip teams decide how fast each core ticks and when it may rest. Faster ticks finish work sooner but use more power and make more heat, so the chip speeds up only when there is work to do.
1 question
Check yourself
A CPU runs at 4 GHz. About how many ticks is that each second?Show the answer
About 4 billion. Giga means billion.
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