Blockchain nodes and their roles

**Blockchain nodes** are individual computers or servers that run the software of a blockchain network. By participating in the network, each node helps maintain the ledger, enforce consensus rules, and provide various services. Below are the main types of nodes and their typical roles: | Node Type | Core Function | Typical Responsibilities | |-----------|----------------|--------------------------| | **Full Node** | Stores the entire blockchain history and validates every block and transaction. | • Downloads and verifies all blocks.<br>• Relays valid transactions/blocks to peers.<br>• Enforces consensus rules (e.g., proof‑of‑work, proof‑of‑stake).<br>• Provides a reliable source of truth for wallets and explorers. | | **Archive Node** | Same as a full node, but also retains historic state data (account balances at every block). | • Enables queries about past states (e.g., “what was an address balance at block 12345”).<br>• Used by block explorers, analytics platforms, and developers needing deep historical data. | | **Lightweight (SPV) Node** | Stores only block headers, not full transaction data. | • Verifies that a transaction is included in a block using Merkle proofs.<br>• Relies on full nodes for detailed data.<br>• Ideal for mobile wallets and low‑resource devices. | | **Mining/Validator Node** | Produces new blocks (PoW miners) or proposes/attests blocks (PoS validators). | • Performs consensus work (hashing, staking, signing).<br>• Earns block rewards/fees.<br>• Must stay online and meet performance/security requirements. | | **Masternode** (specific to some PoS/DPoS chains) | Provides additional services such as instant transactions, privacy mixing, or governance voting. | • Holds a collateral stake (e.g., 1,000 XMR).<br>• Earns a portion of block rewards for providing the service. | | **Relay/Bridge Node** | Connects two separate blockchains, passing messages or assets between them. | • Monitors events on both chains.<br>• Executes cross‑chain logic (e.g., lock‑mint, atomic swaps). | | **Indexer/Analytics Node** | Parses blockchain data into a searchable database. | • Powers explorers, dashboards, and on‑chain analytics tools.<br>• Often runs a full or archive node underneath. | | **API/Service Node** | Exposes RPC/REST endpoints for developers and wallets. | • Handles JSON‑RPC calls (e.g., `eth_getBalance`).<br>• May cache data for faster responses. | ### How Nodes Work Together 1. **Propagation** – When a node receives a new transaction or block, it forwards it to its peers, quickly spreading the data across the network. 2. **Consensus** – Full/validator nodes verify that the data follows the protocol rules. Once enough nodes agree, the block becomes part of the canonical chain. 3. **Redundancy & Security** – Having many independent nodes makes the network resistant to censorship, attacks, and single points of failure. 4. **Specialization** – Not every participant needs to run a full node; light clients can rely on full nodes for data, while miners/validators focus on block production. ### Why Node Diversity Matters - **Decentralization:** More independent operators → less central control. - **Reliability:** If some nodes go offline, others keep the network alive. - **Scalability:** Specialized nodes (e.g., indexers, bridges) off‑load heavy tasks from core consensus nodes. In summary, blockchain nodes are the backbone of any distributed ledger, each playing a distinct role—from validating and storing the entire history, to producing new blocks, to providing lightweight access for end‑users. Their combined operation ensures security, transparency, and resilience of the blockchain ecosystem.