CSS Color

Keyword Colors:

'RGB values' denote specific color names, for instance, red, green, blue, etc, but not every color.

                          
                            p {
                                color: red;
                                background-color: lightblue;
                            }

Hexadecimal Colors:

Hexadecimal values signify colors and for instance, #RRGGBB represents red, green and blue respectively where RR, GG, and BB are two-digit hexadecimal values for red, green and blue.

                          
                            p {
                                color: #ff0000; /* red */
                                background-color: #00ff00; /* green */
                            }

RGB Colors:

An RGB mode, standing for Red, Green, Blue, uses 0 to 255 numbers for each color's intensity.

                          
                            p {
                                color: rgb(255, 0, 0); /* red */
                                background-color: rgb(0, 255, 0); /* green */
                            }

RGBA Colors:

Similar to RGB, but, instead, the numeral alpha is included for transparency and specified as a value between 0 an 1.

                          
                            p {
                                color: rgba(255, 0, 0, 0.5); /* semi-transparent red */
                                background-color: rgba(0, 255, 0, 0.7); /* semi-transparent green */
                            }

HSL and HSLA Colors:

A model like HSL consists of three elements, which are Hue, Saturation, and Lightness. Hue is given a number between 0 and 360 accordingly.

HSLA is pretty much like an alternative of HSL, with an alpha channel for transparency effects.

                          
                            p {
                                color: hsl(0, 100%, 50%); /* red */
                                background-color: hsla(120, 100%, 50%, 0.3); /* semi-transparent green */
                            }

These are both just a few of the various ways to indicate colors on in CSS.

Go for the technique your goal may be or the design of your project!