1. Peer-to-Peer Network

In a blockchain, participants (nodes) are interconnected in a decentralized manner, eliminating the need for a central server. Each node maintains a copy of the entire blockchain, ensuring redundancy and resilience. This structure allows for direct transactions between parties, enhancing security and reducing reliance on intermediaries.

 2. Distributed Ledger System

A distributed ledger is a consensus of replicated, shared, and synchronized digital data geographically spread across multiple sites or institutions. Unlike traditional centralized databases, no central administrator exists, and each participant maintains an identical copy of the ledger, ensuring transparency and fault tolerance. Wikipedia

 3. Key Cryptography

Blockchain employs asymmetric cryptography, where each participant has a public and a private key. The public key is shared openly, while the private key remains confidential. This dual-key system facilitates secure transactions and digital signatures, ensuring authenticity and non-repudiation.

 4. Hashing

Hashing transforms input data of any size into a fixed-length string, known as a hash, using algorithms like SHA-256. Each block in the blockchain contains a hash of the previous block, creating a chain. Any alteration in the data would change the hash, signaling tampering and preserving data integrity.Wikipedia

 5. Proof-of-Work (PoW)

PoW is a consensus mechanism where nodes (miners) compete to solve complex mathematical puzzles. The first to solve the puzzle gets the right to add a new block to the blockchain and is rewarded accordingly. This process secures the network by making it computationally impractical to alter any aspect of the blockchain.

6. Merkle Tree and Merkle Root

A Merkle tree is a binary tree where each leaf node represents a hash of data, and each non-leaf node is a hash of its children. The Merkle root, at the top, is a single hash that represents all the transactions in a block. This structure allows for efficient and secure verification of data integrity. GeeksforGeeks

7. Block Structure

Each block in a blockchain contains:

Block Header: Includes metadata such as the previous block's hash, timestamp, and nonce.

Transaction Counter: Indicates the number of transactions in the block.

Block Size: Specifies the size of the block.

Transactions: The actual transaction data.

This structure ensures that each block is securely linked to its predecessor, forming an immutable chain.

Understanding these core components provides a foundation for delving deeper into blockchain's functionalities and applications. If you have further questions or need more detailed explanations on any of these topics, feel free to ask!