Hexadecimal Colours Red, Green and Blue Hexadecimal numbers are used on web pages to set colours. The colour is defined by its mix of Red, Green and Blue, each of which can be in the range: 0 to 255 (in decimal) , or 00 to FF (in hexadecimal) Because a colour can be made by mixing Red, Green and Blue. So it is called the "RGB Colour System". It is also called an "Additive" colour system, because it starts at black, and then colour is added. Colour Mixer Try mixing your own colours to see how it works (or type values into the hexadecimal or decimal boxes): See Interactive Colour Wheel http://www.mathsisfun.com/numbers/color-wheelinteractive.html Hexadecimals Hexadecimal numbers are "natural" to computers, because computers store and handle binary digits, and four binary digits make one hexadecimal digit (see Binary Digits): Decimal: Binary: 01 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 10 11 100 101 110 111 1000 1001 1010 1011 1100 1101 1110 1111 Hexadecimal: 0 1 2 3 4 5 6 7 8 9 A B C D E F Two Hexadecimal digits together (called a "byte") can make 16×16=256 different levels of colour. 16 Million Colours Because each of the three colours can have values from 0 to 255 (256 possible values), there are: 256 × 256 × 256 = 2563 = 16,777,216 possible colour combinations (and this is why you see claims of "16 Million Colours" on computer equipment) Web Format The format ("notation") used on web pages is #RRGGBB, where RR is how much Red (using two hexadecimal digits), GG is how much Green, and BB how much Blue. Example: a nice shade of blue is made up of: 64/255 Red, 48/255 Green 255/255 (i.e. full) Blue So it is (64,48,255) in decimal, which is equal to (40,30,FF) in hexadecimal and would be coded as #4030FF. This may help you remember: Roses are #FF0000 Violets are #0000FF Just don't forget, Grass is #00FF00, too Some Common Colours Colour Decimal Hexadecimal (Red, Green, Blue) (#RRGGBB) Black (0, 0, 0) #000000 White (255, 255, 255) #FFFFFF Red (255, 0, 0) #FF0000 Green (0, 255, 0) #00FF00 Blue (0, 0, 255) #0000FF Yellow (255, 255, 0) #FFFF00 Cyan (0, 255, 255) #00FFFF Magenta (255, 0, 255) #FF00FF Try entering the hexadecimal code into the colour mixer above, and see what you get (you can copy, then right-click the hexadecimal box, and select "paste"). I have also compiled a much longer list of Hexadecimal Colours and their Names.