I love looking at the motherboard. It's full of little tiny parts, chips, places to plug things in, and bits that stick out through the case of the computer. Over time, they have changed a fair bit but they still do the same job.
When you look at the back of a computer, you can see lots of places where you can plug things in: USBs, printers, headphones, etc. Most of these are on the motherboard and connect to other parts inside.
Central processing unit (CPU)
This is sometimes just called the processor. It's now a tiny component but it has a very important job. It's what makes the whole thing work. Because it does such a big job, it could get quite hot…