Off Camera Hot Shoes
A hot shoe is an accessory holder or accessory shoe on a camera that holds an electrical contact which will allow a flash to be triggered off. On the camera it is usually a clip or a slotted bracket on the top of it that you attach the flash unit to. Small, portable flashes that have contacts on them can be connected to a hot shoe. This will cause the flash to go off when you press the shutter release.
Most cameras have hot shoes built into them, but you can also get portable, hand held hot shoes. These units generally attach to the camera unit with a cord or cable. This allows you to move the flash manually. You can move the flash closer or at a specific angle. You can also move it away from or above the camera or position it for flash bounce. You can buy one of these units for about $40.