What is a CPU?

A Central Processing Unit or CPU is electronic machinery that carries out instructions from programs that allows a computer or other device to perform its tasks.

Navigating the world of computer parts can be daunting for the uninitiated. There are many different components like the hard drive, motherboard, RAM, and GPU, each with unique functions and many variations. But arguably, the most crucial component of them all is the CPU.

What is a CPU (in short answer)?

The term CPU stands for Central Processing Unit. In short, the CPU is electronic machinery that executes instructions from programs so you can call your friends, open your web browser, or write emails. Many people typically ask: "what is a CPU in a laptop or a desktop computer?" not realizing that CPUs are part of other modern devices like tablets, smartphones, DVD players, or smart washing machines too! Regardless of where you find it, the CPU will be completing calculations by utilizing its billions of transistors. These calculations run the software that allows a device to perform its tasks. For example, a CPU in a smart thermostat helps its software adjust heating and cooling temperatures by executing instructions.

What does a CPU do in a computer?

Just to clarify, any programable machine that automatically carries out logical operations or sequences of arithmetic is a computer. In other words, your laptops, desktops, tablets, gaming consoles, and smartphones are all computers. So, what does a CPU do in a computer? Well, it interprets binary signals to complete actions, calculations, and run applications in a three-step process:

  • Fetch: The CPU fetches instructions from the computer’s memory and stores them in a part of its control unit called the Instruction Register (IR).
  • Decode: The CPU sends the instruction from the IR to its instruction decoder. This combinatorial circuit decodes the instruction into signals.
  • Execute: The decoded signals travel to relevant destinations in the CPU for the execution phase.  

A CPU also works with other components. For example, it may take relevant data sent from a video game to a graphics card. The graphics card then processes the information to display on a monitor. Likewise, a CPU helps move data from a computer’s hard drive to its memory for faster access.

Is the CPU the brain of the computer?

Experts often refer to the CPU as the brain when describing computer components in layman terms. While this analogical comparison to a human body accurately depicts the critical nature of a CPU’s role, it doesn't tell the whole story. A CPU doesn’t offer instructions; the software does. In truth, a computer’s software and CPU working together in harmony are the brains of the operation.

What makes a CPU good?

Clock Speed

A clock speed tells you how many instructions a CPU can manage in a second and generally indicates how fast it is. From the 90s to the early 2000s, CPU clock speeds improved significantly with every new generation. However, advancements in clock speeds began to plateau due to extra heat generation and higher power consumption. Here, manufacturers found it more cost-effective to enhance CPUs in other ways, so much so that a modern processor can usually outperform a decade-old processor that has a higher clock speed.


The multi-core processor revolution began with dual-cores and quad-cores. Instead of focusing on advancing clock speed, manufacturers fitted multiple CPUs on one chip. Nowadays, premium CPUs are hitting 32 cores, 64 cores, and more. Such CPUs are an excellent choice for video editors, game streamers, and users of demanding applications, though they may be something of an overkill for the average user.


Hyper-threading is a technological innovation from Intel that allows a single processor core to perform like two by dividing workloads for simultaneous processing. To put it crudely, imagine dividing a hot dog into two and eating both pieces together for faster consumption instead of starting on one end and working your way to the other. Of course, Intel’s competitor AMD has its own version of hyper-threading.

Clock speed vs. Cores

It helps to think of a CPU with a higher clock speed as a sports car and a computer with more cores as a truck. While the sports car will reach its destination faster, a truck will carry more load. Whether you should select a fast processor or a processor with multiple cores depends on your workload. For example, while some apps benefit from multiple cores, others rely on higher clock speed and may not utilize multiple cores.

What does the CPU do in gaming?

The GPU on a graphics card or motherboard renders graphics for a game like landscapes and animations, while a CPU handles calculations for in-game mechanics, artificial intelligence (AI), and inputs from a mouse and keyboard. Not too long ago, games did not take advantage of multiple cores, but modern titles can efficiently utilize over four cores. So, if someone asks you what the best CPU for gaming is, you might tell them to pick a quick multi-threading processor with at least four, if not six cores, that falls in their budget.

Why is my CPU slow?

CPUs can slow down because of aging, overheating, inadequate power or poor ventilation. Some types of malware can also hijack system resources. Check out our article on how to protect your computer from malicious cryptomining to prevent bad actors from using your machine for their monetary gain.

How to maintain a CPU

To keep your CPU in good shape, ensure that your computer’s fans are clean and keep your machine in a ventilated location. For protection against CPU over-use from malware, use reliable antivirus/anti-malware software to protect against resource-stealers like cryptojackers. You may also want to remove some pre-installed software that could unnecessarily take up resources. If you have built your own computer and know how to work with hardware, according to Intel, you should also replace your thermal paste once every few years. Lastly, it also helps to recognize hardware problems that look like malware problems to troubleshoot issues more thoroughly as they arise. 

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