Dye is a substance that changes the color of something by soaking into it. Unlike paint, which sits on the surface, dye actually becomes part of what it colors. When you dye a white T-shirt blue, the blue molecules bond with the fabric's fibers, changing the shirt's color.

People have been dyeing cloth for thousands of years. Ancient civilizations discovered that certain plants, insects, and minerals could create vibrant colors. Purple dye was once so rare and expensive that only royalty could afford purple clothing. Today, most dyes are made in laboratories, making it easy and affordable to dye clothing many different colors.

You can dye many things besides fabric: hair, Easter eggs, leather, wood, and even food. Hair dye changes your hair color temporarily or permanently. Food coloring is a type of dye that makes frosting, cake batter, or drinks more colorful.

The word can also be a noun, as in “fabric dye” or “hair dye.” When something is being colored, you might say it's in the dye bath or that you're dyeing it. Be careful not to confuse dyeing (coloring something) with dying (no longer living), which sounds the same but means something completely different.