Merged mining is a method that lets compatible proof-of-work blockchains share mining work. With auxiliary proof of work (AuxPoW), an auxiliary chain accepts evidence of hashing performed for a parent-chain candidate, while retaining its own ledger and validation rules.
How the chains share work
In the Bitcoin–Namecoin arrangement, a miner commits to auxiliary-block data through the parent candidate's coinbase transaction. Merkle proofs connect that commitment to the parent header. Namecoin checks this evidence and the applicable proof-of-work requirements, together with its own block rules.
The networks must support a compatible mining algorithm and the necessary auxiliary validation. The parent network need not interpret the auxiliary chain's transactions. Sharing work does not merge balances, combine transaction histories, or create a bridge between the assets. Each chain determines block acceptance and rewards under its own rules.
Benefits and security limits
A participating miner can reuse hashing work across chains instead of performing an entirely separate hashing search for each one. Additional node software, block construction, and operational maintenance are still needed; this is not cost-free infrastructure or guaranteed additional income.
An auxiliary chain may attract more mining power, but it does not automatically inherit all of the parent's security. Its protection depends on actual participation and miner incentives. Concentrated control of auxiliary-chain hashrate can remain a risk even when the parent network is much larger.