The vast majority of decentralized finance is now evolving on the Ethereum blockchain. So best to find out exactly what Ethereum is...
Ethereum is a universal, open-source system for decentralized applications. Look at it as a global computer that cannot be turned off.
Software developers can create smart contracts on Ethereum that regulate digital value with a given criteria and can be accessed all over the world.
Many decentralized applications (Dapps) are offering financial services. The foundations of these Dapps are smart contracts created by software programmers.
These smart contracts are then set up on the Ethereum system, where they operate non-stop. Maintaining the digital value and monitoring the latest state is the responsibility of the system.