A diffuser is a device used to disperse essential oils into the air, releasing their scent and their aromatherapeutic effects to be inhaled. The most common type is the aroma lamp, a small tripod that holds a small bowl over a candle or tealight. Water and essential oils are placed in the bowl. When the candle is lit, it heats up the water, gently releasing the volatile vapors of the essential oils into the surrounding air. Devices of this type can contribute to both the ambiance and the atmosphere of a home, and they come in a wide variety of styles to suit any decor, from stark deco to the most rococo and ornamented.
Another common type is the light bulb ring, a ceramic ring that fits on top of a light bulb with a rounded top. The ring has a groove around the top, into which a person can drip essential oils, and the from the bulb evaporates the oils, releasing them into the air. This type of diffuser is handy for situations in which burning a candle might be dangerous or not allowed, such as in an office environment. As a note on etiquette, people who are in shared office space and wish to diffuse essential oils should check with their coworkers for allergies and preferences. It's also important to note that this type of device might not work with compact fluorescent lights, which are usually shaped differently and do not generate as much heat.
A simple unglazed ceramic pot can also be used as a diffuser. This type is typically glazed on the bottom and part way up the sides to protect the surface it are sitting on. Putting water and essential oils in the pot allows the mixture to seep into the ceramic medium and evaporate, releasing the scent and effects of the oils.
Electric devices are also available, and they typically come with absorbent pads that the user soaks in essential oils and place in the machine. Like an air cleaner, this type blows air over the oil-soaked pad and out into the room. These can waste costly essential oils, however, and make a bit of a hum, which can get annoying.