CMYK stands for Cyan, Magenta, Yellow and Key (black). These 4 colours are used in combination in print to lay onto white paper to produce almost any colour required. No colours produce nothing (white), all the colours combined create black and every combination in-between create all the colours you see on the page. RGB stands for Red, Green and Blue. These 3 colours are used for all TV, screen and light based colour on a black screen. No colours produces nothing (black) and all colours at full intensity produce white, with every combination in-between creating all the colours we see. As there are fundamentally different ways to create the colours we see, when RBG images are converted to CMYK during the printing process, some colour changes and undesirable outcomes can occur. It is always recommended to convert all colours to CMYK for most printing products for best results. However, there are some exceptions; RBG produces the most vibrant colours for large large format printing such as Posters. If you are unsure on what colour space your files or images are or what colour space to use for your project, please Contact Us and we will be happy to check your files and/or advise the best colour space to use for your project.