A Kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle. The traditional kayak has a covered deck and one or more cockpits, each seating one paddler. Their cockpit is sometimes covered by a spraydeck (or "skirt") that prevents the entry of water from waves or spray and makes it possible for suitably skilled kayakers, to roll the kayak: that is, to capsize and right it without it filling with water or ejecting the paddler.
Some modern boats vary considerably from a traditional design but still claim the title 'kayak', for instance in eliminating the cockpit by seating the paddler on top of the boat ("sit-on-top" kayaks); having inflated air chambers surrounding the boat; replacing the single hull by twin hulls ("W" kayak), and replacing paddles with other human powered propulsion methods, such as foot-powered rotational propellers and 'flippers'. Kayaks are also being sailed, as well as propelled by means of small electric motors, and even by outboard gas engines, when possible.
The kayak was first made and used by the native Ainu, Aleut and Eskimo hunters in sub-Arctic regions of northeastern Asia, North America and Greenland.
Kayaks (Inuktitut: qajaq (ᖃᔭᖅ [qɑ.'jɑq]), Aleut: Iqyax) were originally developed by the Eskimos. They used the boats to hunt on inland lakes, rivers and coastal waters of the Arctic Ocean, North Atlantic, Bering Sea and North Pacific oceans. These first kayaks were constructed from stitched seal or other animal skins stretched over a wood or whalebone-skeleton frame. (Western Eskimos used wood whereas the eastern Eskimos used whalebone due to the treeless landscape). Kayaks are believed to be at least 4,000 years old. The oldest existing kayaks are exhibited in the North America department of the State Museum of Ethnology in Munich.
Color or colour (see spelling differences) is the visual perceptual property corresponding in humans to the categories called red, blue, yellow, green and others. Color derives from the spectrum of light (distribution of light power versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical specifications of color are also associated with objects, materials, light sources, etc., based on their physical properties such as light absorption, reflection, or emission spectra. By defining a color space, colors can be identified numerically by their coordinates.
Because perception of color stems from the varying spectral sensitivity of different types of cone cells in the retina to different parts of the spectrum, colors may be defined and quantified by the degree to which they stimulate these cells. These physical or physiological quantifications of color, however, do not fully explain the psychophysical perception of color appearance.
The science of color is sometimes called chromatics, chromatography, colorimetry, or simply color science. It includes the perception of color by the human eye and brain, the origin of color in materials, color theory in art, and the physics of electromagnetic radiation in the visible range (that is, what we commonly refer to simply as light).