The CPU (Central Processing Unit) is a microchip, ranked as the brains of computers. His job is to interpret the instructions that come from the hardware and software, so the hardware and software can communicate with each other, for example. CPUs have different kinds (Celeron, Pentium, AMD, etc.) and different speeds (600Mhz, 700Mhz, 1.79 (1790 Mhz) and so on). The CPU is one of the main reasons for buying a computer. The faster the CPU can process instructions faster the computer. However. This is not strictly true. Intel Pentium 4 processor is faster than an Intel Pentium 3, in theory. And the "short version" of the Intel Pentium 4 – Celeron CPU – is supposed to be faster than the Intel Pentium 3. I say supposed, in theory, because it depends on how slow the computer down or speed it up.

An Intel Pentium 2 with 7,200-rpm hard drive is faster than an Intel Pentium 2 with a hard disk of 5400 rpm. And Windows 98SE with 256 megabytes of memory is faster than Windows 98SE with only 64 megabytes of memory. So far, this is as expected. However. You can have a Pentium 2 with 256 MB of memory and a 7200rpm hard drive will be faster than a Pentium 3 with only 64 MB of memory and a 5400rpm hard drive. This is because despite the slower Pentium 2 processes instructions from the instructions are being much faster memory. For example. If a Microsoft Word file on the hard disk is copied in memory, perhaps to the print and / or for editing, copying can be done at intervals of 1 MB. Whereas when you know you have Windows 98SE as much memory as you know you can copy data at intervals of 2 MB for example. With a faster hard drive and moving files, installing software, file indexing and thus also becomes faster. So the memory and hard drive to make the slow CPU.

With time and progress manufacturers have made it possible for the CPU to be divided into two or four parts (cores), known as Dual Core and Quad Core, respectively, which basically means the CPU now has two or four brains use. These core CPU tasks spread amonst themselves, making it possible for a brain (core) to print a document, for example, while another brain (core) handles Internet processing tasks, for example.