Simply stated, “Additive colors (RGB) begin as black and become white as more red, blue, or green light is added. Subtractive colors (CMYK) begin as white. As you add filters to the white light, such as ink, this white light takes on the appearance of color.” – The Paper Mill Store
More on – RGB – “RGB (red, green, and blue) is a model based on light energy. It’s what’s called an “additive model,” meaning adding the highest strength of all the colors of light together will give you white. If your laptop or device were suddenly shut off, your screen would immediately become black because no light would be passing through it. Speaking of computers, RGB is the color space most commonly used to display colors on a computer monitor. That means it is the color space you likely used to build your designs.”
More on – CMYK – “CMYK is a subtractive, pigment-based model. Instead of starting with black, we start with white (like white paper) and the color subtracts from the amount of white you start off seeing.
In CMYK printing, there are four color different plates, each printing a different color of ink: cyan, magenta, yellow, and black. These colors mix together to remove color from white light, producing the image you see.”