Blue dye is a colorant used to give a blue hue to various materials, including fabrics, paper, and food. Historically, it has been derived from natural sources like the indigo plant and woad, which were used for centuries before synthetic alternatives were developed. Today, many blue dyes are produced chemically, allowing for a wider range of shades and improved colorfastness. In addition to textiles, blue dye is also used in cosmetics, art supplies, and even in the food industry to color products like candies and beverages. The safety and regulations surrounding blue dyes vary, with some synthetic dyes being scrutinized for potential health effects, while natural dyes are often considered safer alternatives.