What is a terminal fee?

Excuse me, could you possibly elaborate on the concept of a terminal fee? Is it a specific charge associated with cryptocurrency transactions or is it a broader term that encompasses various financial services? How does it differ from other fees that may be incurred during a transaction? Is it a fixed amount or does it vary depending on the amount being transferred or the specific service being utilized? I'm eager to gain a better understanding of this term and how it impacts the overall cost of conducting financial transactions.