You can tell a lot from the design and color of food packaging. The color of a packet of M&Ms, for example, can tell you whether they’re peanut, regular, crispy, or caramel. And if you’ve ever glanced at the back of a food package, you know they’re full of information: the story of the brand, nutritional figures, ingredients, and serving size. There’s something else printed on the back of most food packaging: several brightly-colored circles or squares that look like some sort of secret language. These shapes aren’t an indication of flavors, vitamins, or minerals. They’re really not there for us consumers at all, but rather, for the printing engineers. The colored circles on food packages can come in a variety of colors: pink, yellow, blue, black, orange, purple, or green, in varying shades of light and dark. Apparently, those colored shapes are called “printer’s color blocks” or “process control patches,” and they’re there to help the printing team who prints the food packaging. When the packaging is printed, technicians use the colored circles to check that the printing ink is the correct color and quality. They compare the color to boxes printed around the world to ensure consistent brand colors. Most printers only use four colors: cyan (blue-green), yellow, magenta, and black. But some printers have extra colors like orange, green, and violet. This helps them match challenging colors like Home Depot orange and FedEx purple. Colored circles on food packages help printers to color match when they’re printing food packaging and retain brand consistency all over the world. That means you can reach for a yellow packet of M&Ms in Shanghai, Sarajevo, or Sydney and know you’ll be getting peanuts; Peanut M&Ms, that is.