At first, cryptocurrencies were seen as mere coins, cash, payment methods. Their use was limited to carry out and receive transactions involving themselves, like any FIAT currency, but gradually, the concept started developing and new functions were included in the newly emerging cryptos, until the appearance of Ethereum, the first cryptocurrency to store intelligent contracts and create tokens and NFTs within its blockchain.
From that moment on, DeFi was born, a financial system trying to provide an alternative to the traditional system, allowing its users to participate in the income generated by a bank, foreign currency exchange office, broker, etc.