There’s something deeply unnerving about how on line retailers, like Amazon for example, seem to know just what many of your interests might be and mange to suggest tempting offers. They seem to have a sort of 6th sense of what some of your eclectic interests might be. So how is it done ?
From prostitution to dealing on the stock exchange, trading has been around for tens of thousands of years. But when did mankind move from a barter system to exchanging goods for bits of metal and paper ?