As its name suggests, under cabinet downlight is lighting that is placed underneath your cabinets like in your kitchen to give you task lighting above your counter tops. I definitely recommend getting this type of lighting hardwired by a licensed electrician, as hardwired lights give a clean, aesthetic look throughout your kitchen, and they free up your kitchen outlets.
under cabinet downlight has several distinct advantages. First, under cabinet lighting is resourceful - rather than needing to install an entire lamp fixture or ceiling fixture, under cabinet lights can be installed directly into a cabinet that is already fixed into place. As a result, under cabinet downlight can be very cost effective, especially when considering the total cost of materials.
Second, under cabinet downlight can be a very efficient use of light. What we mean by efficiency here does not necessarily refer to electrical efficiency (e.g. LED vs halogen), but the fact that under cabinet downlight directs light to where it is needed (i.e. kitchen counter) without much "wasted" light that spills over across the room. When compared to ceiling or table lamps, which disperse light everywhere, under cabinet downlight is a very efficient alternative.
Third, under cabinet downlight is aesthetically pleasing. Not only will it improve the brightness and overall ambiance of your kitchen, it can increase the resale value of your home. One significant advantage here is under cabinet downlight is almost always completely hidden due to the fact that it is mounted on the underside of cabinets. Additionally, since it is typically installed below head level, most occupants will not "look up" into the light and see wires or fixtures. All they see is a nice, bright light being cast downwards towards the kitchen counter.