Apple’s device to implement Mac OS X’s automatic backup, Time Machine over Wifi. The device is nothing (or not much) more than an Apple Airport Extreme Base Station with an internal drive. It is sold in 500GB and 1TB versions. The only difference between versions is the size of the internal drive. I have a terabyte model at home which acts as our wireless base station, an ethernet hub for our networked media drive, and as a Time Machine destination for our various Macs.
image from apple.com
As the device is an Airport Extreme Base Station, it has the following characteristics:
- IEEE 802.11 a/b/g/pre-n base station
- 3-port gigabit switch
- USB port for attaching an external drive or printer, or a hub and multiple devices
- External drive can be shared over AFP or SMB
- External drive can be used as a Time Machine backup destination
It then has a couple of characteristics unique to it:
- Internal drive can be shared and used as a Time Machine backup as well
- Airport utility allows the internal drive to be backed up to an external USB drive
