You can easily find the hex value of any color on your computer screen. It's very similar to the rgb() function in terms of usage. HSL functional notation represents color using hue, saturation, and luminosity. It also accepts percentage value from 0% ( same as 0.0) and 100% (same as 1.0). On the other hand, the alpha channel accepts values from 0.0 (completely transparent) to 1.0 (completely opaque). The red, green, and blue values must be an integer between 0 to 255 (inclusive), or a percentage varying from 0% to 100%. It's defined using the rgb() function which accepts input parameters in the form of primary red, green, and blue components (and an optional alpha channel). RGB functional notation represents colors using red, green, and blue components. It follows the above criteria with an alpha channel specified by 0xaa to control opacity. For instance, #000 (or #000000) is black while #fff (or #ffffff) is white. If you have color #556677, you can simply write it as #567 since it represents 0xrr, 0xgg, and 0xbb respectively. The lower the 0xaa value is, the more translucent the color becomes. It follows the RGB criteria outlined above with an alpha channel that handles the sheerness of the color. It's a fully opaque color with red, green, and blue components as 0xrr, 0xgg, and 0xbb respectively. It's the most common way to describe a numeric color. The string isn't case-sensitive, but it’s conventional to use lower case. Following this character, you specify the colors using hexadecimal digits of a specific color code. Hexadecimal string notation always starts with the character #. These are hexadecimal string notation, RGB functional notation, and HSL functional notation. In CSS, you can use three methods to represent an RGB color. While designing a website or an app, the color scheme matters a lot-it definitely shouldn't be the last thing you consider.