A micropayment is a financial transaction involving a very small sum of money and usually one that occurs online. A number of micropayment systems were proposed and developed in the mid-to-late 1990s, which were ultimately unsuccessful. A second generation of micropayment systems emerged in the 2010s.While micropayments were originally envisioned to involve very small sums of money, practical systems to allow transactions of less than 1 USD have seen little success.