How to Use Hex Codes in Gmail to Show Smiley Faces. Using Gmail is a convenient way to keep in touch with your clients and employees.

Hex codes are especially useful for matching colors in an Illustrator document to those on a Web page, as both HTML and CSS use hexadecimal codes to specify colors.

Hexadecimal format allows us to instruct a computer to display a color using three or six characters. For example, #000 will produce black. But how many ...