Conversion Rate Optimization ( CRO )  is simply method of converting web visitors of a webpage into taking desired action.  That action could be simple as signing up for a newsletter or commonly have them make a purchase.

CRO has nothing to do traffic source,  Instead it has to do with what changes can i make on the page that will make visitors convert.

That's why CRO experts have a claim, " More Profits With Same Adspend"