Summary

The CPU, or Central Processing Unit, is the brain of a computer. Its primary purpose is to execute instructions and perform calculations required to run software and processes. Acting as the control center, it fetches data and instructions from memory, processes them quickly, and then sends results back to memory or other components. 

The CPU's speed and efficiency directly impact a computer's performance. It carries out tasks such as arithmetic operations, logical comparisons, and data movements, ensuring smooth functionality of applications and the operating system. Essentially, the CPU interprets and executes the instructions that make software and applications work, enabling users to interact with their computers effectively.