Color Color Color (American English), or colour (Commonwealth English), is the characteristic of human visual perception described through color "categories", with names such as red, orange, yellow, green, blue, or purple. This perception of color derives from the stimulation of cone cells in the human eye by electromagnetic radiation in the visible spectrum. Color categories and physical specifications of color are associated with objects through the wavelength of the light that is reflected from them. This reflection is governed by the object's physical properties such as light absorption, emission spectra, etc. By defining a color space, colors can be identified numerically
Judo rules Judo rules This article describes the rules of judo. The main sections of the article describe the rules that apply to any situation in which judo is practiced, and those rules which apply only in judo competitions. Separate sections describe the history of the rules of judo, provide links to other sources of information on judo rules, and list the references for this article. The scoring rules in use starting in 2017 are as follows: The following rules are no longer in use: Two types of penalties may be awarded. A "shido" (指導; literally "guidance" or "instruction") is awarded for