Chain Reorganizations Explained: Why Blockchain History Sometimes Changes | Peesh Chopra
When most people think about blockchains, they imagine an immutable ledger where every new block is permanently added to the chain. In reality, blockchain history can occasionally change. Blocks that appeared valid moments earlier may later be replaced by a different branch of the blockchain. This process is known as a chain reorganization , often shortened to chain reorg . Although the term sounds alarming, reorganizations are not necessarily signs of failure. In many blockchain networks, they are a natural consequence of decentralized consensus. Understanding why they happen helps explain how blockchain networks maintain a single shared history despite operating across thousands of independent nodes. Before exploring chain reorganizations, it's helpful to understand the broader consensus mechanisms that allow decentralized networks to agree on a shared history. I cover these concepts in my Blockchain Consensus in Production guide. Why Chain Reorganizations Happen Validato...