I am able to simultaneously activate my internal, external (inserted) card and my ethernet port to access the internet. Is this normal for all of these to be active at once? If so, which one is actually accessing the internet?

Go to your Control Panel and then click "network connections."Double click on them to see their status. This is how you can turn them off individually or see what each is doing.

Or, double click on the little "connected" icon (looks like a computer) in the lower right corner. Then go to properties. At the top you will See "connect using" and it will show you what it is using to connect. You can change it, too.

Yes, it's fine to have them all going at once, though to no particular end.

Thanks for the info, but I know how to do all of that. I was really wanting to know why they could all work at the same time? What's the point?

Why? They operate on separate com ports/channels etc. None interfere with the others, and so there's no reason they shouldn't work simultaneously. To what end, however, is another question. I don't believe there was an "intelligent design" behind the fact that they can work concurrently.

If you're thinking that you might be able to set up a network or something utilizing all of them, there's no need. Any one device has more bandwidth than you could probably use for a network.

As my mom used to say, "it just is."