HTML color codes are used to define the colors of elements in an HTML document. There are several ways to specify colors in HTML, but the most common way is to use hexadecimal color codes.
A hexadecimal color code is a six-digit code that represents a color using a base-16 numbering system. Each hexadecimal digit can have a value from 0 to 9, or from A to F (10 to 15 in decimal). The first digit of the hexadecimal color code represents the amount of red in the color, the second digit represents the amount of green, and the third digit represents the amount of blue.
Here are some examples of hexadecimal color codes:
#000000 represents the color black
#FFFFFF represents the color white
#FF0000 represents the color red
#00FF00 represents the green color
#0000FF represents the color blue
It is also possible to specify colors using the RGB (Red, Green, Blue) model. In this model, each color is represented by a number between 0 and 255, which indicates the amount of each primary color present in the color. For example, the code RGB (255, 0, 0) represents the color red, because there is 255 red and no green or blue.
There are also predefined color names in HTML, such as "red" for red, "green" for green, or "blue" for blue. However, there are only 147 predefined color names in HTML, which may limit the color possibilities.