Color (sometimes misspelled "colour") on computer screens is made up of 3 "primary" colors: red, green and blue.
You will often see this referred to as "RGB." These colors are "additive": zero of all three gives black, while maximum of all three makes white.
Colors by number
Computers work with powers of two. The relevant vocabulary for describing colors uses "hexadecimal", which is base sixteen. Hexadecimal numbers are how geeks count up to 16 (0-15 actually) without using more than one digit. In hexadecimal, 0-16 is counted 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F.
- Using one hex digit for each of the three base colors, the range for each is 0 (zero) to 15 (which is 16 or 24 higher), for a total of 163, or 4,096 possible values.
- using two hex digits for each color, the range for each is 0 (zero) to 255 (which is 256 or 28 higher). This yields a total of 2563, or 16,777,216 values;
Each base color (red, green, and blue) can have a value in one of these ranges.
In HTML, hexadecimal color codes are preceded by "#". Then:
- Using the 0-15 method, a RGB color is represented as #000 for black, through #FFF for white.
- In the 0-255 method, black is #000000 and white is #FFFFFF.
Note that equal amounts of red, green and blue produce various shades of gray (for example #A2A2A2). Pure reds are of the form #XX0000, (where X is one of the valid hexidecimal digits 0-F), pure greens are #00XX00, and pure blue shades are #0000XX. Any color combination can be created using any number from 00 to FF in each of the three positions.
Colors by name
There are also palettes of named colors.
|aqua||#00FFFF||Sample text on black||black||#000000||Sample text||blue||#0000FF||Sample text||fuchsia||#FF00FF||Sample text|
|gray||#808080||Sample text||green||#008000||Sample text||lime||#00FF00||Sample text on black||maroon||#800000||Sample text|
|navy||#000080||Sample text||olive||#808000||Sample text||purple||#800080||Sample text||red||#FF0000||Sample text|
|silver||#C0C0C0||Sample text on black||teal||#008080||Sample text||white||#FFFFFF||Sample text on black||yellow||#FFFF00||Sample text on black|
There is another palette of named colors which might or might not work with various web browsers. (These colors are now generally functional on all browsers; see here).
If you're really picky try here.
Text color coding
Using CSS color attribute:
<span style="color:hex triplet or colour name">text</span>
<span style="color:red">red writing</span>
- red writing
<p style="color:#0F0">green writing</p>
<span style="color:#0000FF">blue writing</span>
- blue writing
This has the advantage that other attributes can be included in the same "span" tag.
The use of the <font color> </font> HTML tags is still valid but deprecated
- <font color="red">RED TEXT</font>
- RED TEXT
- <font color="#0F0">GREEN TEXT</font>
- GREEN TEXT
- <font color="#0000FF">BLUE TEXT</font>
- BLUE TEXT
If you're really lazy then a list of color templates can be found here.
Other use of colors
Colors can also be defined in other html tags, such as table tags. BGCOLOR="#abcxyz" will set the background color of a table, row, or cell when used inside the appropriate tag. Wiki table colors can also be defined using the "style" attribute.
Examples to copy
As with many tricks and tools on computers, copying something you like is often the quickest way to get there.
- In printing, four colours are used: cyan, magenta, yellow and black (yes, black's not really a color but that's the way it goes) referred to as "CMYK"; these are "subtractive": zero of all four gives white while maximum of all four (or maximum of all 3 colors, or just maximum of black) gives black)
- You might like to follow up by reading about Cascading Style Sheets in Wikipedia.