What is a fio request?

Could you elaborate on what a FIO request actually entails? I've heard it mentioned in the context of cryptocurrency transactions but I'm not entirely clear on its specific purpose and functionality. Is it a type of authorization or verification process? Does it involve any specific steps or procedures that need to be followed? Understanding the intricacies of a FIO request seems crucial in ensuring smooth and secure cryptocurrency transactions, so I'd appreciate any clarification you could provide.