Colors are displayed combining RED, GREEN, and BLUE light.
Color Values
HTML colors are defined using a hexadecimal (hex) notation for the combination of Red, Green, and Blue color values (RGB).
The lowest value that can be given to one of the light sources is 0 (hex 00). The highest value is 255 (hex FF).
Hex values are written as 3 double digit numbers, starting with a # sign.
http://www.w3schools.com/Html/html_colors.asp
Web Standard Color Names
The World Wide Web Consortium (W3C) has listed 16 valid color names for HTML and CSS:
aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, purple, red, silver, teal, white, and yellow.
If you want to use other colors, you should specify their HEX value.
http://www.w3schools.com/Html/html_colors.asp
16 Million Different Colors
The combination of Red, Green and Blue values from 0 to 255 gives a total of more than 16 million different colors to play with (256 x 256 x 256).
Most modern monitors are capable of displaying at least 16384 different colors.
If you look at the color table below, you will see the result of varying the red light from 0 to 255, while keeping the green and blue light at zero.
To see a full list of color mixes when the red light varies from 0 to 255, click on one of the hex or rgb values below.
http://www.w3schools.com/Html/html_colors.asp
Interactive Tools
http://www.w3schools.com/Html/tryit.asp?filename=tryhtml_colorhex
http://www.colorschemer.com/online.html – Interactive color wheel that produce RGB and Hexadecimal # for you
http://www.computerhope.com/htmcolor.htm – Color Chart
Additional Resources
What is Hexadecimal?
In mathematics and computer science, hexadecimal (also base-16, hexa, or hex) is a numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F (or a through f) to represent values ten to fifteen.
Its primary use is as a human-friendly representation of binary coded values, so it is often used in digital electronics and computer engineering. Since each hexadecimal digit represents four binary digits (bits)—also called a nibble—it is a compact and easily translated shorthand to express values in base two.
Hex triplet
A hex triplet is a six-digit, three-byte hexadecimal number used in HTML, CSS, SVG, and other computing applications, to represent colors. The bytes represent the red, green and blue components of the color. One byte represents a number in the range 00 to FF (in hexadecimal notation), or 0 to 255 in decimal notation. This represents the least (0) to the most (255) intensity of each of the color components. The hex triplet is formed by concatenating three bytes in hexadecimal notation, in the following order:
- Byte 1: red value (color type red)
- Byte 2: green value (color type green)
- Byte 3: blue value (color type blue)
For example, consider the color where the red/green/blue values are decimal numbers: red=36, green=104, blue=160 (a greyish-blue color). The decimal numbers 36, 104 and 160 are equivalent to the hexadecimal numbers 24, 68 and A0 respectively. The hex triplet is obtained by concatenating the 6 hexadecimal digits together, 2468A0 in this example.
Note that if any one of the three color values is less than 16 (decimal) or 10 (hex), it must be represented with a leading zero so that the triplet always has exactly six digits. For example, the decimal triplet 4, 8, 16 would be represented by the hex digits 04, 08, 10, forming the hex triplet 040810.
The number of colors that can be represented by this system is
An abbreviated, three (hexadecimal) digit form is sometimes used.[5] Expanding this form to the six-digit form is as simple as doubling each digit: 09C becomes 0099CC. This allows each color value to cover its full range from 00 to FF. The three-digit form is described in the CSS specification, not in HTML. As a result, the three digit form in an attribute other than “style” is not interpreted as a valid color in some browsers.[citation needed]
http://en.wikipedia.org/wiki/Web_colors
