A CPU or "Central Processing Unit" is like a brain for computers! CPU's are made of many different pieces that all work together to make a computer do tasks.
CPU's are made up of small transistors, which are like very tiny switches that can be turned on or off like a light switch. The transistors are grouped together to form "integrated circuits" or "chips," which then work together to form the CPU. The CPU is the part of the computer that tells the other parts what to do, like an orchestra conductor.
To make a CPU, engineers first design a plan of how they want it to work. They draw out the different parts on a plan called a "blueprint." They use this blueprint to build the actual CPU by putting together millions of those small transistors discussed before. The transistors are connected in a way that enables them to read and store information like numbers and letters, and then tell the other parts what to do with this information.
Once the CPU is built, it can then be put inside the computer to help it work. The CPU will be the "brain" that tells the other parts what to do based on the instructions that were given to it.