Centralised crypto is a code-based asset built to be used as a medium of exchange. Additional units are added by mining. Everyone is able to do this by using their a device. Mining uses a large amount of time and electricity, though. A high-powered computer is also required, to do this successfully. However, Ripple is a centralised asset, which is unmineable. A limited amount of coins were created by the company and this limit will never be exceeded.