[Tech Help] External HDDs w/ Cloud

I'm looking for an external HDD to backup some files, preferably with these capabilities:

1. Can remotely access the files over the internet similar to cloud or Dropbox
2. Can auto-backup designated folders periodically

First one is a priority. Second one is a convenience. I've heard terms like NAS and RAID thrown around, but not exactly sure on what they are or do. And with Black Friday coming up, I figure I can get a decent deal on something to do this, I just don't know what I need.

 

Thanks for the reply. I had already ended up buying a 2-bay QNAP NAS. Still haven't figured out how to set up the cloud because I can't access it from a remote network. I'm pretty ignorant when it comes to computer networks.

But, I also bought a 1 TB WD Ultra Passport, that works with Dropbox. So, maybe that'll be easier.