Primary colors are red, blue and yellow. I'm not really sure why this answer needs thirty words, but um. Yeah. Red is um...? vibrant. Blue is pretty good too. Yellow! What can be said about yellow that hasn't been said already? Yeah.
Primary colors are the ones that cannot be mixed or formed by any combination of other colors. There are 3 primary colors namely red, blue and yellow. But by mixing 2 primary colors, secondary colors can be made, like red (primary) and yellow (primary) when mixed together gives orange (secondary).