Warm colors refer to the colors that reminds one of the sun, sunset or of daytime. Examples of warm colors are red, yellow and orange, and these colors are referred to as such because they resemble fire and evoke feelings of warmth. Cool colors include shades of blue, green and violet, and the colors are said to remind one of cool things like water or grass.
Warm and cool colors are one of the elements of the color theory, which is a set of principles and of practical guidance about colors and their use in visual arts. The color theory serves a common ground from which everyone can discuss practically everything related to colors and how the human brain processes, perceives and interprets the colors.
Although the concept of warm or cool colors is hardly discussed in modern colorimetry, it is still very much a part of current visual and design art practices. Apart from the colors mentioned, shades of brown and tan are also considered warm colors.
In interior design and fashion, warm colors are said to be stimulating while cool colors are relaxing. Warm colors are also believed to advance or are more active while cool colors are said to recede. The combination of warm and cool colors can be used to emphasize the perception of depth.