Explain the role of nodes in a blockchain network.

Nodes in a blockchain network play a critical role in maintaining the decentralized and distributed nature of the system. A blockchain is essentially a distributed ledger that records transactions across a network of computers, which are the nodes. Each node in a blockchain network serves several key functions:

1. Data Storage: Nodes store a copy of the entire blockchain ledger locally. This ledger contains a record of every transaction that has ever occurred on the network. By storing the entire blockchain, nodes ensure data redundancy and help maintain the integrity of the ledger.
2. Transaction Validation: Nodes validate transactions before adding them to the blockchain. When a new transaction is broadcasted to the network, each node independently verifies its validity by checking various criteria such as digital signatures, transaction inputs, and consensus rules. Only valid transactions are included in the next block of the blockchain.
3. Consensus Participation: Nodes participate in the consensus mechanism of the blockchain network to agree on the state of the ledger. Depending on the consensus algorithm (e.g., Proof of Work, Proof of Stake), nodes contribute computational power or stake their cryptocurrency to help validate transactions and secure the network. Through consensus, nodes reach an agreement on the order of transactions and ensure that the ledger is immutable and tamper-resistant.
4. Propagation of Transactions and Blocks: Nodes propagate transactions and newly mined blocks to other nodes in the network. This ensures that all nodes have the latest information about transactions and the current state of the blockchain. Propagation helps maintain synchronization across the network and prevents discrepancies in the ledger.
5. Network Connectivity and Communication: Nodes maintain network connectivity by communicating with other nodes in the network. They exchange information about transactions, blocks, and network status using a peer-to-peer protocol. This communication enables the decentralized nature of the blockchain network, as there is no central authority controlling the flow of information.
6. Wallet Functionality: Some nodes also function as wallets, allowing users to store, send, and receive cryptocurrency. These nodes interact directly with the blockchain network to execute transactions on behalf of users and manage their cryptocurrency holdings securely.

Nodes are the backbone of a blockchain network, responsible for storing data, validating transactions, maintaining consensus, propagating information, and facilitating communication among participants. Their distributed and decentralized nature ensures the security, transparency, and reliability of the blockchain network.