This video by 99Bitcoins gives an introduction to decentralized finance, or defi. Traditional financial services are operated by companies and organizations with centralized authority. This means customers might be at the mercy of unscrupulous individuals. Defi is intended to take that power away and put into computer programs called smart contracts. Smart contracts can only be controlled by a consensus of distributed stakeholders. However, defi is still in its early days, so there are risks and bugs that need to be worked out before the mainstream can use it.