A CPU, or Central Processing Unit, is the primary component in a computer that performs most of the calculations and processes data. It is often referred to as the "brain" of the computer. CPUs are manufactured by companies like Intel and AMD and are responsible for the overall performance of a computer.

One of the key specifications of a CPU is its clock speed, which is measured in gigahertz (GHz). This indicates how many cycles per second the CPU can execute. However, clock speed alone is not always an accurate indicator of performance, as other factors such as the number of cores and cache size can also affect the overall speed.

CPUs come in different models, with varying numbers of cores and cache sizes. More cores generally mean better multitasking capabilities, as each core can handle separate tasks simultaneously. Cache is a small amount of memory that the CPU uses to store frequently accessed data for quick retrieval.

TDP, or Thermal Design Power, is another important specification to consider when choosing a CPU. TDP refers to the maximum amount of heat that the CPU can generate and is measured in watts. CPUs with higher TDPs tend to be more powerful but also consume more power and generate more heat, which can require more advanced cooling solutions.

Overclocking is another factor to consider, as it allows users to increase the clock speed of their CPU beyond its default specifications. This can improve performance but also increases power consumption and heat output, which may require additional cooling solutions.

Intel and AMD are the two main CPU manufacturers for desktop PCs. Intel CPUs are known for their strong single-core performance, while AMD CPUs tend to offer more cores and better multithreaded performance. Both companies offer a wide range of CPU models at different price points to suit different user needs and budgets.