RGB

RGB is an additive color model.
It is defined by rgb( red, green, blue ).
Where red, green, blue are numbers between ( 0 - 255 ) i.e. 8 bits of information about each color.
255 is the brightest color and 0 is the darkest color.

We can add one more channel to the RGB color model.
i.e. the alpha channel.
and the color model is defined by rgba( red, green, blue, alpha ).
Where alpha is a number between ( 0 - 1 ) which is the information about transparency of the color.
1 is opaque and 0 is completely transparent. By default alpha is 1.

Syntax

                
    rgb( red, green, blue )
    rgb( red, green, blue, alpha )
    rgba( red, green, blue, alpha )    
            

Example