Which component is essential for executing instructions within a computer?

The Central Processing Unit (CPU) is the component that is essential for executing instructions within a computer. The CPU is often referred to as the "brain" of the computer; it performs calculations, manages data, and executes instructions from programs and applications. It retrieves instructions from memory, processes them, and then sends signals to other parts of the computer to perform the tasks specified by those instructions. This capability makes the CPU a critical component for overall system performance and functionality.

In contrast, the memory module serves as a temporary storage area for data and instructions being used by the CPU but does not execute those instructions itself. The power supply unit provides the necessary electrical power to all components of the computer but does not involve itself in processing instructions. The graphics card, while important for handling visual output and rendering graphics, plays a different role and does not perform general instruction execution like the CPU. Thus, the CPU stands out as the key component responsible for executing the instructions that drive the operation of a computer.