Which are the components of one blockchain system ?

A blockchain system is composed of several key components that work together to ensure its functionality, security, and integrity. Here are the main components:

1. Nodes: These are individual computers or devices that participate in the blockchain network. They maintain copies of the blockchain, validate transactions, and propagate information across the network.
2. Blocks: Blocks are data structures that store a set of transactions. Each block contains a timestamp, a reference to the previous block (the “parent” block), and a cryptographic hash of its contents, linking it to the previous block and forming a chain.
3. Transactions: Transactions are the data entries recorded in the blockchain. They typically represent the transfer of assets or information between participants and are the fundamental units of value or action in the blockchain.
4. Consensus Mechanism: This is a protocol used to achieve agreement among nodes on the state of the blockchain. Common consensus mechanisms include:
   • Proof of Work (PoW): Requires nodes (miners) to solve complex mathematical problems to validate transactions and create new blocks.
   • Proof of Stake (PoS): Nodes are selected to create new blocks based on the amount of cryptocurrency they hold and are willing to “stake” as collateral.
   • Delegated Proof of Stake (DPoS): Stakeholders elect a small number of delegates who are responsible for validating transactions and creating blocks.
   • Practical Byzantine Fault Tolerance (PBFT): Nodes reach consensus through a voting process, which is robust against a certain number of faulty or malicious nodes.
5. Ledger: The blockchain itself acts as a distributed ledger. It is a record of all transactions that have occurred on the network, stored in an immutable and transparent manner.
6. Smart Contracts: These are self-executing contracts with the terms of the agreement directly written into code. They automatically enforce and execute the terms of the contract when predefined conditions are met.
7. Cryptographic Hash Functions: These are mathematical algorithms that take input data (such as a block’s contents) and produce a fixed-size string of characters, which appears random. Hash functions ensure data integrity and security by making it virtually impossible to alter the data without changing the hash.
8. Public and Private Keys: In a blockchain system, public keys are used to receive assets, while private keys are used to sign transactions and prove ownership. They work together in asymmetric cryptography to secure transactions and access blockchain data.
9. Consensus Rules: These are the set of rules that nodes follow to validate transactions and blocks. They ensure that all participants in the network agree on the state of the blockchain.
10. Network Protocols: These are the communication protocols used by nodes to exchange information, such as transaction data, block updates, and network status. They ensure that all nodes can communicate and synchronize with each other effectively.
11. Decentralized Applications (DApps): These are applications that run on a blockchain network, utilizing its decentralized and secure nature to provide various services, such as decentralized finance (DeFi) or non-fungible tokens (NFTs).
12. Token Standards: In some blockchain systems, especially those supporting smart contracts, specific standards define how tokens should behave. Examples include ERC-20 (for fungible tokens) and ERC-721 (for non-fungible tokens) on the Ethereum blockchain.

These components work together to create a secure, transparent, and decentralized system that allows for the efficient and trustless exchange of value and information.