There are literally millions of different colours which can be used in graphic design and unlimited ways of combining them. It is essential that a graphic designer develops a thorough understanding of colour in order to use it to its greatest advantage. 
There are a variety of different ways colour can be formatted or organised for computing applications.

Some of the main colour formats used for computer graphic design are:

CMYK
CMYK is the colour combination used in printing. It is also known as “Process Colours” or “4 Colour Process”. CMYK stands for the colours Cyan, Magenta, Yellow and Key - which is black. By combining different percentages of these colours many, many different variations of colours can be created. If you look at a printed brochure, magazine etc. that has been printed using this process (most are) under a magnifying glass, you can see a series of dots that are made up of CYMK. Your eyes normally blur these small dots and that is what creates the different colours you see. CYMK is based on the chemistry of mixing translucent inks rather than opaque paints.

RGB
This is the colour combination used in electronic devices such as computers, digital cameras, tablets and televisions. For example, most .jpg files you come across will be in RGB because they are mainly viewed on a screen of some kind. RGB stands for Red, Green and Blue. Similarly to CMYK, combining different amounts of the colours will produce different colours. However, unlike CMYK, the more intense the colours the lighter the colour appears to be. The reason for this difference is because the Red, Green and Blue are actually light sources, not inks. The maximum reading of each light is 255 and the minimum is zero. If all 3 colours are set to zero, then zero light is coming through and you will see black. If all 3 colours are set to 255, then 100% light is coming through and you will see white. If Blue and Red are set to zero and Green is set to 255, then only the Green light is showing and you will see only green. If that Green is then set to 200, the green will be darker, because less light is coming through, and so on.

PMS Colours
PMS or “Pantone Matching System” is a system made up of 1,114 different inks. Each of the 1,114 different inks has its own PMS Number. This system is used in printing to create consistency between printing jobs. PMS colours are also referred to in the industry as Pantone colours, special colours, and spot colours. When designers are creating a logo or brand ID etc. they will choose 1 or a series of special colours that will be associated with the company they are designing for. The reason for this to create a solid look and feel that can be carried across all visual elements of the business. 

Most established companies have already chosen these colours and they are used to help distinguish brands from each other, just like football teams or countries do with their flags. For example, the Blue, Yellow and Green of the Brazilian Football team or Red being the prominent colour in the Chinese flag. 

There are many advantages to using PMS colours which include reducing the amount of materials used, and sometimes cost in printing. For example, the ‘Bill's Paving’ logo below, is made up of Black and PMS 465, so when printing only 2 colours are needed. If that was printed as CMYK, then it would need 4 colours and the printer could not guarantee consistency.

Foil
You may of come across printed designs that also have elements of metal. These are using either foil or metallic ink. If it has a very metallic look and feel to it, most likely it is foil. Foil is literally as it sounds - a metal foil, which is a very thin layer of metal that has been transferred to the design using a heated stamp process.

Spot Varnish
“Varnish” is another element that can be used in printing and can be considered when creating a design. Varnish comes in 2 main variations - Gloss and Matt. These are normally clear, but will change the appearance of the colour underneath by changing the texture to either gloss or matt. The “Spot” refers to the fact that the varnish is treated the same as an ink in the printing process. That means if say you had a page that had 3 boxes in the middle of the design which had photos in them, and the rest of the design was a solid colour with some text, you can apply a spot gloss varnish to the image boxes only, thus making those images really jump out giving the design a more dynamic feel. If this was printed in CMYK, then it would actually become a 5 colour job - CMYK + Spot Varnish. 

Another way to use spot varnish is to use it to create shapes or elements on a page. For example, a designer is creating a brochure for a bicycle company and a part of the branding involves solid lines representing the spokes of a bicycle wheel. The designer wants to use these bicycle spokes like elements, but feels as a colour it is too distracting from the content of the brochure. In these circumstances they may choose to put the spokes in only the spot varnish and have that randomly sneaking in from the corner of each page, running over parts of images etc. Doing this kind of thing won’t affect legibility of content and will create fun, or even sometimes a sophisticated look.


HEX COLOURS
Hex is short for Hexidecimal. Hexidecimal numbers are a base-16 numbering system that can be used to define colours on a web page. A Hex number is written with digits from 0-9 followed by letters from A to F. For example:

• White is represented by writing ff ff ff  or  #ffffff
• Red is  written as ff 00 00  or  #ff0000
• Black is written by writing   00 00 00 or  #000000