Drip irrigation is a technique for delivering water to plants that is more efficient than traditional methods like sprinkler, hose or bucket. It is a system of perforated pipes that transport water from a water source to the roots of plants, either on the ground surface or in containers. A timer controls when the water is delivered. This allows you to set up your system so that it delivers water during specific times of day or night, and only when it’s needed by the plants.
Drip systems usually consist of tubing, emitters, and a timer. The tubing lays on the ground or in soil to transport water to the roots. The emitters are placed at the base of plants and send water out of a small hole. A timer controls when the water is delivered. This allows you to set up your system so that it delivers water during specific times of day or night, and only when it's needed by the plants.
Here is a great video for how to install a drip irrigation system on a raised bed.