What are merchant fees?

Excuse me, could you please elaborate on what merchant fees are? I'm quite curious to understand the intricacies behind this term, especially in the context of cryptocurrency and finance. Are these fees charged to businesses that accept cryptocurrency payments? If so, how do they differ from traditional merchant fees associated with credit card or bank transfers? And furthermore, what factors contribute to the determination of these fees? I'd appreciate it if you could provide a comprehensive yet concise explanation.