An A21 bulb is a type of light bulb commonly used in domestic lighting applications. It is named A21 because it has a diameter of 21-eighths of an inch or approximately 2.625 inches.

In the lighting industry, “Ingress Protection” (IP) refers to a rating system that indicates the level of protection provided by a lighting fixture against solid objects and water.

Recessed lighting, also known as can lighting or downlighting, is a type of lighting fixture that is installed into a ceiling or wall cavity, creating a clean and streamlined look.

A fluorescent tube, also known as a fluorescent lamp or tube light, is a type of lighting fixture that operates using a low-pressure, mercury-vapor gas discharge.

Valance lighting is a type of architectural lighting that involves the use of light sources concealed behind a horizontal shield, typically positioned at the top of a window or along a wall.

Triac dimming, also known as phase-cut dimming, is a method used in the lighting industry to adjust the brightness of lights, particularly incandescent or halogen lights.

Ultraviolet (UV) light is a form of electromagnetic radiation that falls between visible light and X-rays on the electromagnetic spectrum. It has a shorter wavelength and higher energy than visible light, making it invisible to the human eye.

Light, in the context of the lighting, refers to electromagnetic radiation that is visible to the human eye. It is a form of energy that enables us to perceive our surroundings and plays a crucial role in illumination and visual perception.

Warm white is a specific color temperature range of light. It refers to a softer hue of white light with a hint of red and yellow tones, creating a warm and cozy ambiance.

High-Intensity Discharge (HID) is a type of gas discharge lamp widely used in the lighting industry. These lamps produce light by creating an electric arc between two electrodes through an ionized gas.