What is the TX fee in Crypto?

Excuse me, could you please explain what the TX fee is in the world of cryptocurrency? I'm relatively new to this space and have been hearing the term frequently but haven't quite grasped its significance yet. Is it a type of fee that's charged whenever a transaction is made, and if so, how does it differ from other fees associated with cryptocurrency trading or holding? Additionally, does the TX fee vary depending on the type of cryptocurrency or the platform being used? Your insights would be greatly appreciated.