Block Propagation

Block propagation is the process of relaying a newly mined block across Bitcoin's peer-to-peer network so that every node receives, validates, and adds it to its copy of the chain. Speed matters intensely: until a block reaches the rest of the network, other miners may keep working on the previous tip, and any block they find in that window competes with the one already mined.

Why propagation speed protects miners

The longer a block takes to spread, the higher the chance another miner finds a competing block at the same height, producing a fork that resolves into one winner and one orphan block. A miner whose block loses that race forfeits the reward entirely. This orphan risk is the core reason propagation latency is treated as a first-class engineering concern, and it historically pushed pools toward shortcuts like empty-block and SPV mining.

How the network accelerated propagation

Several techniques cut propagation time. Compact block relay (BIP 152) sends short transaction identifiers instead of full transactions, since most peers already hold the transactions in their mempool. Dedicated high-speed relay networks and improvements to validation pipelines further reduced the gap between a block being found and being accepted everywhere.

Propagation delay is the practical driver behind several mining behaviors and risks; it is measured as propagation delay and is a major contributor to the rate of stale blocks on the network.