Is downloadable content protected??

I finally figured out how to get downloadable content attached to a product.

It seems to work fine (except for an error message related to shipping).

I can see the link to download, and it downloads just fine.

My question is, what is to prevent someone from simply copying the URL and sharing that with other people?

Here is the URL I was given after testing the checkout process:
http://wichitaoilpainting.com/store/pub/.vsnqbqglvvnqzufzwzl/springbreeze2.pdf

Now, this is a free product so I don't mind people downloading it. I want to know if this link works for everyone. If so, maybe I've done something wrong.

you can only download it x amount of times over x amount of days,
that is a virtual link, the file dosne actualy reside in the pub folder

In admin > Catalog > Attributes Controller, you can set the number of days a download will be available, and the number of downloads allowed.

You might want to check this tutorial

AND

This one