A coinbase transaction is a unique type of transaction that can only be created by a miner. This type of transaction has no inputs, and there is one created with each block that is mined in Jax.Network. In other words, this is the transaction that rewards a miner with the block reward for their work. Any transaction fees collected by the miner are also sent in this transaction. The coinbase transaction is always the first transaction in a block in Jax.Network.