Financial tools and apps powered by blockchain
DeFi is used to denote Decentralized Finance, and broadly describes a variety of financial applications and solutions that are made possible with blockchain technology. By replacing centralized services with decentralized autonomous organizations, anyone and everyone can benefit. This is commonly referred to as DAO - a Decentralized Autonomous Organization, like MakerDAO. Most DeFi solutions are made with the intent of providing service better than what today's financial institutions offer.
Early cryptocurrencies like Bitcoin showed that you could remove the middleman to transfer wealth. DeFi seeks to improve the speed, privacy and sophistication of such transactions, using smart contracts. These are preprogrammed transactions that only execute if certain conditions are met. DeFi widens the use case for cryptocurrencies several magnitudes beyond Bitcoin's ledger system.
Most of today's DeFi solutions are built with the Ethereum blockchain, since Ethereum has the most extensive developer base. However, similar blockchains like Binance Smart Chain and Solana have seen increased use as DeFi becomes more popular.