A very easy way to think of NAS is like this: The hard drive in your computer is attached to the motherboard by a SATA (Serial Advanced Technology Attachment) cable. NAS is a hard drive attached to the motherboard by an Ethernet cable instead of a SATA cable. SATA cables are limited in length to one meter and Ethernet cables are limited to 100 meters. In addition to using an Ethernet cable NAS devices communicate via IP or Internet Protocol. Thus, a NAS disk storage device can be accessed from anywhere in the world over the Internet or from another room in your house over your LAN (Local Area Network). NAS devices appear on a computer just like the C: drive on Windows but with another letter such as E: or F:. On Mac OS X a NAS drive mounts on the desktop just like the Macintosh HD.
The advantages of a NAS disk storage device are many. The two important advantages for audiophiles are noise reduction and data redundancy. Hard drive noise is eliminated because a NAS device can be placed outside of the listening room. Data redundancy is even more important in my opinion. A NAS device allows you to store your music files in a RAID array with built-in fault tolerance. RAID is a Redundant Array of Inexpensive Disks that appear as one disk to the computer. Almost all current NAS devices offer differing types of RAID configurations.
Note: This explanation has been extremely simplified. Using a NAS device is not as easy and requires some computer skills to configure. More articles will follow about configuring and using NAS devices.