Pantone sells mixed inks in a bucket. Printing presses tend to only have cyan, magenta, yellow, black ink in them. The density of those inks varies naturally as

Pantone sells mixed inks in a bucket. Printing presses tend to only have cyan, magenta, yellow, black ink in them. The density of those inks varies naturally as a printing press runs. That variation isn't kind to business identity colors. It's not kind to photos either but human vision helps adapt to these variations, with some limits. Specific colored ink mixed in a bucket is much more stable on press, minimal variation. There are other spot color systems such as Toyo, and Focoltone. But at least in the U.S. Pantone is the most common system.