What is a 1394 connection?

"1394" refers to the number of the IEEE standard created for "Firewire", a high speed serial wired communications protocol developed by Apple Computer to transfer digital data over short distances, such as between computers and external hard disks. Serial means that the signal is carried over a single pair of wires known as a twisted pair, using low voltage differential signaling, a method that supports both high speed and good noise immunity. Additional wires carry ground and power. Prior systems used parallel wiring with 8 or more wires carrying a byte at a time, but at lower bit rates. The cables were bulky and expensive, hence the desire for a serial standard. The original standard, Firewire 400, supported 400 Mbps, a later version, Firewire 800, 800 Mbps (using additional wires, but still many fewer than parallel interfaces). Similar to USB 2.0, Firewire is generally faster, and supports daisy chaining and hot swapping. Additional information may be found at HowStuffWorks.com or Wikipedia under "Firewire".