UV Coating is a clear liquid spread over the paper like ink and then cured instantly with ultraviolet light.
It can be used as a spot covering to accent a particular image on the sheet or as an overall (flood) coating, this is called spot UV.
UV coating gives more protection and sheen than aqueous coating (AQ). However, it is more difficult to recycle than the other coatings.
Keep in mind that it is a thick coating that may occasionally crack when scored or folded.