Outdoor lighting is perhaps the most budget friendly way to add that finishing touch to any project. Two types of lighting are available. Low voltage (12 volt) systems can be found in any local home improvement store. Low voltage systems will come with a transformer that will plug into an exterior outlet, and reduce the current to the applicable desired wattage. Low voltage systems typically cost the least, and require no electrical permit or electrician to install. Low voltage systems are normally not installed with a switch, they normally run from a light sensor, timer, or keypad located on the transformer. Digital transformers are now available that provide a much more sleek, user friendly look and feel.
If you are considering a roofed deck or covered patio, hardwired fixtures are more common. These typically consist of a combination of recessed can lights, track lighting, and outdoor ceiling fans. All of the above are typically switched from the interior, dimmer capable, and can be installed for a reasonable price. The options don't stop there, you'll even see one project on this site that incorporated 220 volt exterior space heaters, mounted in the ceiling and controlled via remote or from the homeowner's PC!!
Low voltage lighting is the most commonly used lighting in our projects. It is an adapted version of landscape lighting and requires an exterior outlet. Low voltage lighting can really add the "finishing touch" to a project, a nice combination of step or rail post lights makes any deck more friendly in the evenings. LED lighting is also available from several of the vendors we use. LED provides extended bulb life and more brilliant light.
Generally speaking, we only install hardwired lighting in roof projects. Can lights, track lighting, and wall lighting are all options that nicely dress up a covered patio or deck. Hard wired is normally 110 volt, same current source that interior fixtures operate on. These light systems are commonly installed on dimmers, and provide the amount of light one needs to use the exterior space more like a room. While low voltage lighting is more ambience and perimeter lighting, hard wired sources are what we would consider "functional" lighting.