How do you pay for your food or coffee? Cash or money is what we are using currently. Back in the old days we use barter system, which is basically exchanging goods. Before currency is invented we are actually having difficulties in getting the things we need. When currency or money came out, we saw a lot of different types which evolved from vary material to represent currency or money. Lately the most interesting currency is bitcoin. This is one currency which did not mention if the infographic. I suppose it will take a longer time before people can actually accept bitcoin as a currency. But first bitcoin will have to survive as daily basic usage to exchange goods. Another idea or theory about currency is that perhaps maybe one day the world will be using only one type of currency. In other words, instead of having US dollar, Japan Yen and British pound, we will be using only one currency for all. The concept is basically the same as the launching of Euro currency which combining several currencies of Europe.