What does CYMK stand for. And what exactly is it and what is it used for? I know that it something to do with color, but that's it. Thanks.

CMYK is print colors. Cyan, Magenta, Yellow, and, I don't know why, but, K is Black. Those are the colors of four color printing, and the same that is in your color printer.

Just in case you want to know, RGB is also print colors. Red, green, and blue.

RGB does stand for Red,Green Blue but they are not regarded as "print" colours when used in Photoshop.In photoshop RGB and CMYK are used to define two different colour systems, Additive & Subtractive.Additive is a way we see colour with direct light,such as the colour on a tv screen .Its called additive because when you add all the colours in light together to get white.Subtractive is the colour system used not only in printing,but also in traditional painting where the more colours(pigments) you have the closer you get to black, hence the name as you subtract colours to get white. Printing uses the subtractive system and uses the four coloured inks Cyan,Magenta,Yellow and Black..(k for black comes from the old printing term of Key or Keyline to describe the black plate.) Moniters and TV,s use the Additive system ,combining three coloured lights red,green and blue.Because of factors such as luminosity not all colours can translate from RGB to CMYK.This is why those amazing light effects on the computer screen just look like washed out paper when printed. So if your work is intended for onscreen viewing just stick to RGB,but if you intend to print it you should work either in CMYK or at least with the CMYK preview on to avoid disapointment.

Coooool. Thanks. That's exactly what I wanted to know.

Wow! I never knew that. Thanks DLM!

Wow! I never knew that. Thanks DLM!

Also if you use the color picker in Photoshop and you pick a color ouside the CYMK range, PS pops up the little "!" in a box near your before and after color boxes, if you then click on the "!" PS will set it to the closest printable color, or at least what it thinks is the closest. Biggest disadvantage of working in CYMK is it takes 1/3 more memory for you image, as I'm sure dlm knows.

Jims correct on both counts CMYK does increase file size, mainly due to the fact that you have an extra channel in CMYK mode.It is an important point that he raises,especially for Poser post production people as if you have saved the Poser file as a Tiff you already have an extra channel where the mask has saved as an Alpha channel.This means your starting to get into some very large file sizes and if you were to:- for example,be entering the Zygote Calender contest where the final image is going to be a CMYK 11" x 8.5" image at 300dpi it starts to become almost unworkable on a smaller machine. Another disadvantage is that a number of the photoshop filters only work in RGB mode. I sometimes do work on video covers that are to be printed and to be honest all I do is work in RGB mode with the CMYK preview switched on,to give me a better idea of the final image and keep in mind the fact that it will look a little duller without the screen light behind it.When I,m finished I convert it to CMYK and hope for the best.So far I,ve got away with it.(touch wood)

Also when printhouses print in CMYK they save $$ because they only use one ink for black, not 3 ie: To make black in RGB space you would have to use 100% R 100% G 100% B = 300% ink used.