> For the complete documentation index, see [llms.txt](https://sandcastle.gitbook.io/sand-castle-finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sandcastle.gitbook.io/sand-castle-finance/flash-loans/what-is-a-flash-loan.md).

# 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.