Indicates which method the product uses to connect to the computer. SCSI methods are generally the fastest, but also potentially the most difficult to set up, especially when you have several other items connected or installed. SCSI needs a special card installed to support the product. Most PC and new Macs don't have one so you may need to add this. Parallel is the slowest method of data transfer that's normally used to connect a printer to the computer If you also have a scanner or older card reader there's usually an adaptor to run it from the same connection point as the printer. This can protrude further out of the back of the computer so make sure you have the space to allow this. USB and Firewire are the new, easier methods of connection. Firewire is more popular on MAC platforms and is the fastest system, but also currently the least popular. Both recognize that an item has been attached and install necessary software from the supplied CD, using simple help menus. Both can be connected and disconnected with the computer and peripheral turned on. Unlike SCSI or Parallel, where both have to be switched off.