# What is a flash loan?

A flash loan is a type of loan where a user borrows assets with no upfront collateral and returns the borrowed assets within the same blockchain transaction([Chainlink](https://chain.link/education-hub/flash-loans) 2023). 

Within SandCastle, a flash loan allows for a user to borrow from as many lending pools as desired as long as all of the pools are then paid correctly.