The correct answer to this question is CPU. Standing for central processing unit, the CPU is the most important part of the computer, for it is where the calculations take place. There are two components of the CPU. The first is the arithmetic logic unit. This component is where arithmetic and logical operations are performed.
The second component is the control unit. Here, instructions are extracted, decoded, and executed. In modern computers, CPUs are small and square. They will contain multiple connectors, made of metallic, on the side. It is inserted into the CPU socket and must have the pin side down. This socket is found on the motherboard.