NAS stands for Network Attached Storage.

It is a device with one or more hard drives that attaches directly to your network. Because it is used primarily for file sharing, it does not have a full blown Operating System, and is relatively easy to administer.

The NAS device pictured below, has 8 hard drives.

[Linked Image from files.qnap.com]

"The illiterate of the 21st century will not be those who cannot read and write, but those who cannot learn, unlearn, and relearn." ~ Alvin Toffler