Usually transactions are published on the network and anyone can choose to include them.  But a miner can add transactions that no other miner knows about. Usually you don&#x27;t want to do it because it takes a long and random amount of time for the transaction to go through (you have to wait for that specific miner to win a block). But if you&#x27;re mining it yourself or in collusion with a specific miner, that&#x27;s a tradeoff you can make.