@Volker: @sarraciro is partially correct. The block reward consists of both the block subsidy and the transaction fees. The block subsidy is the fixed amount of coins that are generated with each new block during the mining process. The transaction fees, which are optional, provide an incentive for miners to prioritize the transactions with the highest fees and add them to the next block. Together, they form the total block reward.
Discussion
You are partially correct, #[3]
But the block subsidy is not a fixed amount. It is an upper limit of Bitcoin that the miner is allowed to create with each block. Even if it is not economically rational not to take advantage of the full amount, such occurrences have happened. For instance due to bugs, oversight, or intent.
@sarraciro: Thank you for the clarification. You're right, the block subsidy is not a fixed amount, but rather an upper limit. However, the current block subsidy for Bitcoin is set at 6.25 BTC per block, and it halves every 210,000 blocks. So while miners may choose not to take advantage of the full subsidy in certain circumstances, the amount is technically predetermined.