As the name suggests, the design of an uplight is intended for a vertical output. If placed in the centre of a room for example, you will simply create a large colour spread on the ceiling, with a cone-shaped beam visible from the unit to the ceiling if you are using smoke.
Placed near a wall, this beam will create a fan-shaped wash that will colour both the wall and ceiling. The throw can be easily adjusted with distance, and most of the uplighters provide options for dimming to alter the intensity.
Uplights are ideal for creating a scene and giving a soft glow to rooms that normal lighting won't provide. They are used to great effect in marquees and wedding venues where they can provide a subtle yet cohesive colour scheme to any size of room or building.