Section 2 // ●○ Level: Medium Quick Links: 1: What is web3? 3: Smart contracts | Dashboard: Web3 Starter Pack
<aside> 🥡 KEY TAKEAWAY Blockchain is a digitally distributed, decentralized public ledger that exists across a network.
</aside>
Blockchain is the backbone of Web3 - a chain of blocks that contain information, a distributed ledger completely open and public to anyone.
Each piece of data or transaction that occurs is recorded as a block of data. The growing list of blocks (records) are securely linked together using cryptography.
Each block contains:
✅ a cryptographic hash of the previous block
✅ a timestamp to prove the transaction data existence when the block was published to get into the hash
✅ a transaction data
The chain is formed as each block contains information about the previous to it.
<aside> 🔒 Blockchains are resistant to modification of their data. Once recorded, the data in any given block can not be altered retroactively without altering all subsequent blocks.
</aside>
The blockchains are managed by peer-to-peer (p2p) network for use as a publicly distributed ledger. The nodes collectively adhere to a protocol to communicate and validate new blocks.
Blockchain networks are an entire distributed ecosystem of users, node operators, developers and miners. The network is driven by system of aligned incentives and joint consensus protocols/mechanisms. All the parties vote on how to process a set of transactions i.e. how to create the next block. Then the block with majority votes is the one that is permanently written on the chain.
A consensus is general agreement. To reach consensus means that at least 51% of the nodes on the network agree on the next state of it. Other terms for consensus mechanisms are consensus protocols or consensus algorithms.