What is a flash loan?

Could you please elaborate on what exactly a flash loan is? As someone new to the cryptocurrency world, I'm curious to understand the mechanics behind this concept. How does it differ from traditional lending practices? What are the potential risks and benefits associated with utilizing flash loans? I'm also interested in knowing if there are any specific platforms or protocols that facilitate flash loans and what kind of collateral is typically required. Additionally, could you provide some real-world examples or use cases of flash loans in action? Thank you in advance for your detailed explanation.