An ethernet hard drive is a hard disk that is directly plugged in or connected to a network. These are different than traditional hard disks in that the storage can be accessed by many devices, not just the computer that it's plugged into. These devices can be computers, laptops, servers, or even other storage devices. Ethernet drives are often referred to as a NAS, or network attached storage, however "Ethernet hard drive", network drive, or simply shared storage are all acceptable. Another classification of ethernet drives are SANs, or storage area networks. These are dedicated networks of storage devices that are generally for high-end applications. SAN's are generally accessed by high-end servers and need extremely quick and reliable access to data. Some common uses for ethernet hard drives are for backing up files, storing files centrally, serving media, or just for more general storage for documents - much like internal hard drives.

Ethernet drives can come in many forms and with many options. As the size increases, it's more likely that the drive you purchase will actually be 2 drives in an enclosure. These two drives each have an identical copy of the data. This protects your data in the event that one of the drives were to unexpectedly fail. There are ethernet drives that are very large but only contain one drive; this is acceptable, but be aware of the risk you run in case the drive dies. I generally only use these types of drives for backing up data to, not storing frequently accessed or extremely important data.

Did you know that Ethernet drives can be assembled by anyone? There are kits available on the market for taking any internal drives and making it an ethernet drive. These devices are referred to as €NAS enclosures€. External hard drive enclosures are similar, but are meant to directly connect to your computer via USB, not the network. Either of these enclosures generally require little more than a screwdriver to assemble; there are several models available with a variety of features for you to chose from.

Some of the higher-end ethernet hard drives have advanced options and can be expanded beyond the drive inside their enclosure. These network drives actually have a USB port on them that allow for more drives to be attached in order to expand the available storage amount. These external hard drives can then be used to extend the amount of data available on the ethernet drive, but can also be used to backup all the existing data on the networked drive. This is a great way to protect your data for a relatively low price as compared to backing up to many DVD's or out to the internet.