A recessed light or downlight (also named pot light in Canadian English, sometimes can light (for canister light) in American English) is a light fixture that is installed into a hollow opening in a ceiling. When installed it appears to have light shining from a hole in the ceiling, concentrating the light in a downward direction as a broad floodlight or narrow spotlight..
There are three parts to a recessed lighting fixture: housing, trim and bulb. The trim is the visible portion of the light. It is the insert that is seen when looking up into the fixture, and also includes the thin lining around the edge of the light.
The earliest recessed lights were developed in the 1950s by Ivan Kirlin of the Kirlin Company, Detroit,Michigan.
Recessed lighting offers the advantages of being a hidden light source and energy efficiency. However, the tradeoff is that they are relatively permanent and may be unflattering. (From Wikipedia, the free encyclopedia)