What is a Flash Loan?
Flash loans are a feature designed for developers, due to the technical knowledge required to execute one. Flash Loans allow you to borrow any available amount of assets without putting up any collateral, as long as the liquidity is returned to the protocol within one block transaction. To do a Flash Loan, you will need to build a contract that requests a Flash Loan. The contract will then need to execute the instructed steps and pay back the loan + interest and fees all within the same transaction.
The interesting thing about this type of loan: It is done without a need of a third party institution. It is a de-centralized transaction. This is a primary appeal of the world of cryptocurrency.
Here is a video describing the concept: