Centralised crypto is a digital asset designed to work as a medium of exchange. Additional coins can be added via mining. Everyone may get involved if they've access to a computer. Mining uses a large amount of hours and electrical power, however. A fast machine is also required, to mine profitably. Conversely, Ripple is a centralised coin, which is unmineable. A limited supply of coins were created by the company and this limit will never be added to.