When humans developed, people used to use barter system so that the same person doesn’t have to do all the work by himself. This improved mass production, and cost savings. So in a village, there is one potter, one farmer, one fisher man, one ironsmith etc etc, and all these people together exchange everything everyone make and they are all happy. This gave way to currency, gold and silver coins and prices fixed against the value of gold and silver. This ended when currency values were fixed, and these currencies were now called paper money.
When the currency controllers found it difficult to control the paper monty, the new plastic money is evolving, which lets the banks know who is psending how much. When paper money goes extinct, the controllers will have total control, and this will avoid black money rotation that supports these terrorist groups in afghanistan.
So, to accept plastic money, a seller needs a system that is called a POS or a Point of Sale system. These POS systems have a tiny billing device and inventory management systems in higher priced models, with which the buyer is billed, and the card is swiped to deduct the money from the card account, and transfered to the seller’s bank account.