What is a mintmark on a coin?

I'm curious, could you please explain to me what a mintmark is on a coin? I understand that it's some sort of identifying mark, but I'm not entirely sure of its purpose or significance. Is it used to indicate where the coin was minted, or does it serve some other purpose? Additionally, how can one go about identifying the specific mintmark on a coin? I'd appreciate any insights you could offer on this topic.