The Four Digit Hex Color can be used as the shorthand of 8 Digit Hex Color. Four Digit Hex color can be used to define the color of your elements with the CSS like 8 Digit Hex Color. There are 8 character in 8 digit hex color that shrinks to 4 in 4 digit hex color but performance is the same as the color. In the 4 digits the 4 characters followed by the hash(#) like #RGBA. Here the R define the Red, G define the Green, B define the Blue and the A define the Alpha Channel that effects on how much transparent it will be.
Note: Here the Red, Green, and Blue define the colors with less variant compare to 8 and 6 digit hex color and last character represent Alpha channel.