ELI5: Explain Like I'm 5

Post office box (electricity)

Okay kiddo, so let's talk about post office boxes and electricity. You know how you have a mailbox at your house where the mailman delivers your letters and packages? Well, some people don't have a mailbox at their house or they don't want to give out their home address to everyone. That's where a post office box comes in handy.

A post office box is a little metal box or locker that you can rent from the post office. It has a special address, like a regular house address, but instead of delivering the mail to your house, the mailman puts it in your post office box. So you can go to the post office anytime, unlock your box with a key, and get your mail. It's like having your own personal mailbox at the post office.

Now, let's talk about electricity. You know how you turn on the lights or your favorite toy with a switch or a button? Well, all those things need electricity to work. Electricity is like invisible magic that powers everything from your mom's hairdryer to the TV in your living room.

When you rent a post office box, you don't need electricity to use it. It's just a box to hold your mail. But sometimes, people need electricity for other things, like charging their phone or running a small business. That's when they rent a post office box with what's called a "contract postal unit" or CPU.

A CPU is like a little store inside the post office. You can rent a post office box with a CPU to get access to electrical outlets and other services. It's like a mini-office where you can work, print documents, or even ship packages without having to leave the post office.

So, in short, a post office box is a special address at the post office where you can rent a little metal box to hold your mail. But if you need electricity or other services, you can rent a box with a CPU to get access to these things. It's like your own personal office space in the post office!