When you create global colours from scratch, you can set these to be spot colours.
In professional printing, spot colours can be used instead of CMYK process colours when your artwork contains a very limited colour set. By setting these colours to be spot colours, print costs can be reduced significantly. You may also be able to accurately reproduce colours otherwise impossible with process colours.
As well as setting a global colour to be a spot colour, you can use pre-supplied PANTONEĀ® colours, which will automatically become a global spot colour in the Swatches panel's document palette when applied.