Commercial Electric Ultra Slim 4 in. Color Selectable New Construction and Remodel Canless Recessed

4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5.

4 is the smallest square number > 1, the smallest semiprime and composite number, and the 3rd highly composite number.

The number 4 is considered unlucky in many East Asian cultures.

Color (American English) or colour (British English, Commonwealth English) is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object's light absorption, reflection, emission spectra, and interference. For most humans, colors are perceived in the visible light spectrum with three types of cone cells (trichromacy). Other animals may have a different number of cone cell types or have eyes sensitive to different wavelengths, such as bees that can distinguish ultraviolet, and thus have a different color sensitivity range. Animal perception of color originates from different light wavelength or spectral sensitivity in cone cell types, which is then processed by the brain.

Colors have perceived properties such as hue, colorfulness (saturation), and luminance. Colors can also be additively mixed (commonly used for actual light) or subtractively mixed (commonly used for materials). If the colors are mixed in the right proportions, because of metamerism, they may look the same as a single-wavelength light. For convenience, colors can be organized in a color space, which when being abstracted as a mathematical color model can assign each region of color with a corresponding set of numbers. As such, color spaces are an essential tool for color reproduction in print, photography, computer monitors, and television. The most well-known color models are RGB, CMYK, YUV, HSL, and HSV.

Because the perception of color is an important aspect of human life, different colors have been associated with emotions, activity, and nationality. Names of color regions in different cultures can have different, sometimes overlapping areas. In visual arts, color theory is used to govern the use of colors in an aesthetically pleasing and harmonious way. The theory of color includes the color complements; color balance; and classification of primary colors (traditionally red, yellow, blue), secondary colors (traditionally orange, green, purple), and tertiary colors. The study of colors in general is called color science.

Commercial may refer to:

• a dose of advertising conveyed through media (such as radio or television)
  • Radio advertisement
  • Television advertisement
• (adjective for) commerce, a system of voluntary exchange of products and services
  • (adjective for) trade, the trading of something of economic value such as goods, services, information or money
• Two functional constituencies in elections for the Legislative Council of Hong Kong:
  • Commercial (First)
  • Commercial (Second)
• Commercial (album), a 2009 album by Los Amigos Invisibles
• Commercial broadcasting
• Commercial style or early Chicago school, an American architectural style
• Commercial Drive, Vancouver, a road in Vancouver, British Columbia, Canada
• Commercial Township, New Jersey, in Cumberland County, New Jersey

Construction is a general term meaning the art and science of forming objects, systems, or organizations. It comes from the Latin word constructio (from com- "together" and struere "to pile up") and Old French construction. To 'construct' is a verb: the act of building, and the noun is construction: how something is built or the nature of its structure.

In its most widely used context, construction covers the processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the asset is built and ready for use. Construction also covers repairs and maintenance work, any works to expand, extend and improve the asset, and its eventual demolition, dismantling or decommissioning.

The construction industry contributes significantly to many countries' gross domestic products (GDP). Global expenditure on construction activities was about $4 trillion in 2012. In 2022, expenditure on the construction industry exceeded $11 trillion a year, equivalent to about 13 percent of global GDP. This spending was forecasted to rise to around $14.8 trillion in 2030.

The construction industry promotes economic development and brings many non-monetary benefits to many countries, but it is one of the most hazardous industries. For example, about 20% (1,061) of US industry fatalities in 2019 happened in construction.