&gt;  In particular, I&#x27;d like to understand whether mining fees are paid for executing contracts or for solving hashes or for both<p>I believe the answer is both. Miners get a rewarded for finding a valid block of 5 ETH (typical PoW style reward) and they also receive the transactions fees paid by users of the network. And in Ethereum the cost of a transaction is determined by its &#x27;gas&#x27; cost, which is based on how computationally expensive the transaction is.