🧱 What is Blockchain?
Blockchain is a type of distributed ledger technology (DLT) that records information in a way that's secure, transparent, and immutable (can’t be changed). It’s the backbone of cryptocurrencies like Bitcoin, Ethereum, and BNB.
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📦 Key Pieces of Blockchain
1. Block
Each block contains:
A list of transactions
A timestamp
A reference (hash) to the previous block
A unique hash for itself
Think of it as a page in a ledger.
2. Chain
Blocks are linked in order using cryptographic hashes.
Once a block is added, it becomes part of the chain and cannot be changed.
3. Nodes
Computers (called nodes) in the network validate and store copies of the blockchain.
They ensure decentralization — no central authority controls the data.
4. Consensus Mechanism
A method to agree on which transactions are valid.
Common types:
Proof of Work (PoW) – used by Bitcoin
Proof of Stake (PoS) – used by Ethereum 2.0
Delegated PoS, BFT, etc.
5. Smart Contracts
Programs that automatically execute actions when certain conditions are met.
Used heavily in Ethereum and BNB Smart Chain.