Look on your desk, in your draws you probably by now are the proud owner of at least one USB drive.
What's on that drive? Nothing, a few files, PowerPoint, a PDF, link to a website.
Most of the time that's it, you wipe off those files and use it to store your own stuff!
Now imagine if you used the power of that drive, it's got a memory, it has a unique number, it can be setup to communicate, it can store stuff that is useful and it can present it in an easy way on and off line.