[Day 9] 6. Blockchain

Blockchain is like a chain made of blocks. Each block holds some information, and the blocks are connected in a sequence. You can store anything inside these blocks (like data, records, or transactions). The key thing about blockchain is its integrity, which means that once something is stored, it’s almost impossible to change it. This makes it secure and reliable.

The main building block of blockchain is something called a Hashing Algorithm. This is a special way of turning data into a fixed-length value, which helps in linking blocks together securely.

A block contains the following:

1. Block Number: Every block has a number that shows its position in the blockchain.
2. Data: This is the actual information that you want to store.
3. Previous Hash: Each block remembers the "hash" of the previous block. This links the blocks together like a chain.
4. Date/Time: The exact moment the block was created.
5. Nonce: A random value added to the block to ensure that the block’s hash is unique.
6. Hash: A unique identifier (like a digital fingerprint) for the current block. It’s created using the data inside the block and the previous hash.

The first block in a blockchain is called the Genesis Block. Since it’s the starting point, it doesn’t have a previous block, so its previous hash is set to zero.

Nonce:

A nonce is a random value that is used in blockchain mining to help generate a valid hash for the block. It ensures that the hash of the block is unique and can’t be easily guessed or reproduced. The nonce plays a critical role in making blockchain secure.