Wie funktioniert die Bezahlung per Bitcoin?

Could you please explain in detail how payments are processed using Bitcoin? How does the system ensure that transactions are secure and verifiable? What are the key steps involved in initiating and completing a Bitcoin payment? How does the blockchain technology play a role in facilitating these transactions? Are there any fees associated with Bitcoin payments, and if so, how are they calculated? Additionally, how does the value of Bitcoin fluctuate, and how does it impact the final amount received by the recipient of a Bitcoin payment?