How are exchange rates determined?

Excuse me, could you elaborate on how exchange rates for cryptocurrencies are typically determined? Are they set by a central authority, or do they fluctuate based on market forces such as supply and demand? Is there a formula or algorithm that's commonly used to calculate these rates, or is it more of a complex interplay between various factors? Understanding the mechanisms behind cryptocurrency exchange rates is crucial for investors and traders alike, so I'd appreciate your insights on this topic.