HTML colors are specified using defined color name keywords or RGB, HEX, HSL, RGBA, HSLA values.
For example the color green has the HEX color code #00FF00, that is also RGB(0,255,0), which is '0' red, '255' green, and '0' blue. The color codes can be used to change the color for the text and the background on a web page.
<!DOCTYPE html>
<html>
<body>
<h1 style="background-color:Tomato;"><font color="Gold">Color Tomato</font></h1>
<h1 style="background-color:Orange;"><font color="Indigo">Color Orange</font></h1>
<h1 style="background-color:Blue;"><font color="White">Color Blue</font></h1>
<h1 style="background-color:Green;">Color Green</h1>
<h1 style="background-color:Gray;"><font color="Blue">Color Gray</font></h1>
<h1 style="background-color:Violet;"><font color="White">Color Violet</font></h1>
<h1 style="background-color:LightGray;">Color LightGray</h1>
</body>
</html>