Decentralized Finance or "DeFi" refers to a range of decentralized protocols building open financial infrastructure. Most of them are built on top of a blockchain and can be executed without the need of a middleman ensuring that the individuals are the sole custodian of their assets at all times. However, it is worth mentioning that there are different levels of decentralization. For example, some protocols have centralized price feeds or a central administer platform. This is why some people prefer to call it open finance.