This you'll find inside the box and like everything to follow, it's attached to the motherboard somehow. This is called RAM. It's kind of like our own short-term memory. It's plugged into the motherboard and does 2 things:
1. It remembers stuff the CPU tells it.
2. It tells the CPU the same things later on.
RAM is fast and can only remember a few things. The problem with this short-term memory is that it forgets things really quickly.