What is a coiled remote cord for Nikon Speedlights?

The question says it all, i just need to understand what it does to speedlights. How it works, how effective it is if i use it, and if the cord is in place, does the flash necessarily have to mount on the Body of the dSLR or not?

Many event shooters use what is called a flash bracket and the sync cord connects from the hot shoe to the flash mounted on the flash bracket.

SC-29 TTL model number

Some speed lights are studio lights and the main one has a sync cord attached. This cord can be coiled like a telephone headset cord or straight. When you say "remote" that indicated that the cord is connected from the main flash head to the camera, and all the other flash units fire in sync when the main flash goes off.

If you have a speed light that is designed for a camera, most fire through the connection in the camera's hot shoe. However if you want better lighting control most of us get a camera bracket that accepts the camera and elevates the flash higher than the camera lens. This puts shadows that appear behind subjects with camera attached flashes lower out of picture area and a more pleasant picture results. For this set up you need a flash-to-camera shoe cord. And this cord coiled or not is probably the cord that you are referring to.