The answer to this question can be super long and technical but I’ll give you the cliff notes version!

RGB Color:
Web graphics, web pages, digital images and just about any image that is meant to be viewed on a screen (a device that is backlit) is typically in RGB (Red, Green, Blue) color mode.  Since RGB color profiles rely on a light source that displays them, RGB modes can display over 16.7 million colors including super bright fluorescent hues and it is called an “additive process” because it uses light to create colors.  When all combined together, R G B, they create the color white o your screen.

CMYK Color:
CMYK mode is a color mode used by printers and is stands for Cyan, Magenta, Yellow, Key (black) in which colors are created by a pigment (dye) instead of light.  Combining all these colors is called a “subtractive process” that once all colors are combined with each other creates the color black.

So why do I have to print my artwork in CMYK color mode?
Because inks don’t have a light source illuminating behind them, therefore we need to dye the substrate (paper, shirt, vinyl, or item to be printed on) with pigment inks and CMYK is the color format major printers use.  If it’s meant to ever be printed, design your artwork in CMYK and be careful, converting from RGB to CMYK may yield in a slight variation of color tone and brightness so it’s great practice to always start off in CMYK when you can to eliminate that conversion difference that occurs.

*DTF Printing although it uses CMYK printers, goes through a special process algorithm in a RIP software to handle converting RGB files into the CMYK printer output.  So submitting DTF prints and transfers as RGB is fully acceptable.