How Does Blockchain Work? Under the Hood of Distributed Systems

Understanding the Step-by-Step Flow

When someone speaks of a blockchain "working," they are describing an orchestration of networking, applied mathematics, and cryptographic validation. Let us trace the journey of a transaction from initiation to final inclusion in the ledger.

Step 1: Transaction Creation & Digital Signature

A user initiates a state change (such as sending units of value or interacting with a contract). Their client software cryptographically signs this payload using their private key via algorithms like ECDSA (Elliptic Curve Digital Signature Algorithm) or Ed25519. The signature proves ownership without disclosing the secret key.

Step 2: Gossip to the Mempool

The transaction is broadcast to neighbor nodes in the peer-to-peer network. Each receiving node validates basic criteria (e.g., valid signature, sufficient balance) before adding it to its local mempool (memory pool of unconfirmed transactions) and relaying it outward.

User Sign -> Node Mempool -> Peer Gossip -> Validator Proposes Block -> Consensus Achieved -> State Updated

Step 3: Block Proposal & Consensus

Designated nodes (miners in Proof of Work, validators in Proof of Stake) select a batch of transactions from their mempool. They compute the Merkle tree root and assemble a candidate block. Through consensus rules, one valid block is chosen and broadcast.

Step 4: Block Verification & State Finality

Every independent full node checks that the proposed block conforms strictly to all consensus rules: valid proofs, legitimate transactions, no double-spending, and correct parent hashes. If valid, the block is appended locally.