Define person of colour

Now I know some people are offended with being called a person of colour and I'm not posting this to troll or tick people off but am genuinely interested to know, what classes or defines a person of colour? Can someone who is middle eastern call themselves coloured? What about those who are oriental? I'm curious as I I have heard many Asians don't refer to themselves as white yet having pale skin...so that would mean it doesn't depend on the colour of their skin but racial features? What is everyone's opinions?