What is Blockchain?
Blockchain is essentially a distributed database that stores records (transactions) across multiple computers in a network. Think of it like a shared Google Sheet that hundreds of computers maintain simultaneously—no single company or person controls it.

The name comes from its structure: data is organized in blocks, with each new block cryptographically linked to the previous one, forming a continuous chain.

Core Characteristics
Decentralization: Unlike traditional databases controlled by one organization (like your bank's database), blockchain distributes copies across many computers called nodes. Each node has the full transaction history.

Immutability: Once data is recorded and confirmed, it's nearly impossible to change. Each block contains a unique cryptographic hash (like a fingerprint) generated from its contents plus the previous block's hash. If someone tries to tamper with an old block, its hash changes, breaking the chain and alerting the network.

Transparency: Everyone on the network can see the same ledger, creating trust without needing a central authority like a bank.

How Transactions Work
When you make a transaction:

Your transaction gets broadcast to all nodes in the network

Nodes verify the transaction using preset rules

Valid transactions get grouped into a new block

The block gets added to the chain after consensus

All nodes update their copy of the blockchain

This verification process (called mining in some blockchains) ensures no one can double-spend or fake transactions.

Real-World Analogy from Web2
Think of blockchain like Git for financial transactions:

Traditional banking = saving files locally on one computer (centralized)

Blockchain = a distributed Git repository where thousands of developers (nodes) each have the full commit history, and new commits require consensus before merging

Just as Git makes every code change traceable and permanent, blockchain makes every transaction traceable and permanent.

Solana is a specific implementation of blockchain technology that uses the account model. While other blockchains like Bitcoin focus mainly on simple transfers, Solana's architecture (separating programs from data, requiring upfront account declarations) enables it to process thousands of transactions per second