What does CPU stand for?
Quick answer
CPU stands for central processing unit. It’s the main chip in a computer, phone or tablet that carries out instructions from programs, doing calculations and making decisions billions of times per second. It’s often called the computer’s “brain.”
What a CPU does
Every CPU repeats a simple cycle billions of times a second:
- Fetch an instruction from memory.
- Decode it to work out what to do.
- Execute it, for example adding two numbers.
- Store the result.
Key specs explained
| Spec | Meaning |
|---|---|
| Cores | Independent processing units on one chip; more cores handle more tasks at once |
| Clock speed (GHz) | How many cycles per second; 3 GHz = 3 billion cycles per second |
| Threads | Tasks a core can juggle at the same time |
| Cache | Ultra-fast memory built into the CPU |
Want to check yours? Here’s how many cores your processor has.
CPU vs GPU vs RAM
| Part | Job |
|---|---|
| CPU | General-purpose “brain”; handles a few complex tasks quickly |
| GPU (graphics processing unit) | Handles thousands of simple tasks in parallel; great for graphics, games and AI |
| RAM | Short-term working memory; see what RAM stands for |
A brief history
- 1971: Intel’s 4004, the first commercial microprocessor, had about 2,300 transistors.
- Today’s chips have tens of billions of transistors, each just a few nanometers wide.
Main CPU makers
- Intel and AMD for most Windows PCs (using the x86 design)
- Apple (M-series chips) and Qualcomm using ARM designs, which are common in phones and increasingly in laptops
For the bigger picture, see what a computer is. If your CPU is always busy, read why your computer is so slow.
Still curious?
Jump to a random question from the archive.