Color hex code is a digital representation of colors using a combination of six alphanumeric characters. It is commonly used in web design and graphic design to specify exact colors. In a PDF format, color hex codes can be used to ensure consistency and accuracy in color reproduction. By including color hex codes in a PDF, designers can easily reference and reproduce specific shades, making it easier to maintain brand consistency across different platforms. This can help create cohesive and visually appealing designs that resonate with the audience.