Colour blindness affects many people world wide and surprisingly many of those who are affected don't even realise that they have a problem. 

How can it be that colour blind people go undiagnosed? You would be surprised just how easy it is for a colour blind person to go right through childhood without even realising that they have a problem.

And what do colour blind people actually see?

Read one person's account of how colour blindness affects him in  How I (colour blind person) see the world