Many packages are printed using the familiar CMYK system: cyan, magenta, yellow, and black. By layering these inks in different proportions, printing equipment can reproduce photographs, logos, backgrounds, and thousands of different shades.

During high-speed production, printers need ways to check that those colors remain consistent. Small control patches can help machines or technicians evaluate ink density, color balance, and other printing conditions. Registration marks may also help confirm that different printed layers are lining up correctly instead of creating blurry or offset images.

Not every colored mark serves exactly the same purpose, and packaging methods vary between manufacturers and printing systems. Some packages may also use additional spot colors beyond CMYK, while others may not display visible control marks on the finished section at all. What matters is that these marks are generally intended for production and quality control—not as a message to shoppers.

So those colorful squares are not a reliable guide to sugar, additives, preservatives, food quality, or how “healthy” a product is. For that information, the useful places remain the ingredient list and nutrition label. The mysterious little colors usually tell the printer far more about the package than they tell you about the food inside.