LMD GHOST, short for Longest Minimum Delay GHOST, is the rulebook used by nodes in the Ethereum blockchain to agree on the “true” state of the network. LMD GHOST guides nodes to pick the correct path, even when forks (conflicting blocks) happen.

How LMD GHOST Works

Weighting the Paths: Each block gets a “weight” based on how many validators (computers running Ethereum) agree it’s valid. The more validators agree on a path, the heavier it is.

Following the Leader: Nodes start at the “justified” block, the one with the most weight. Then, they compare each child block, checking which has the highest weight.

Breaking Ties: If two child blocks have the same weight, LMD GHOST looks for the one with the “minimum delay.” This means the child block that was finalized (approved by validators) the fastest. This helps break ties and avoid getting stuck in forks.

Repeating the Process: Nodes keep moving down the chosen path, repeating steps 2 and 3 until they reach the latest block. By following LMD GHOST, nodes all agree on the same valid chain of blocks, keeping the network in sync.

Benefits of LMD GHOST

• Fast consensus: LMD GHOST quickly finalizes blocks, making the network efficient.

• Resilience: It can handle forks and malicious attacks without compromising the network.

• Fairness: Every validator has an equal chance to be heard and contribute to the consensus.

LMD GHOST is a complex concept, but its core function is simple: it helps nodes in the Ethereum network agree on the right path, ensuring everyone sees the same version of the blockchain.