The definition of black has a lot to do with how you are publishing – in print or online.
Print publication uses a four-plate scheme to create colors on the page. This process layers four inks – cyan, magenta, yellow and black – to create every color combination, giving each hue a specific CMYK color value. This even applies to different shades of black.
Online, color is made from combining red, green and blue. Both RGB and HEX values are based on these three colors, which are used as the standard for how digital screens (from televisions to computers) display color.
Pure Black vs. Black