Consensus Algorithms: How Blockchains Reach Agreement

A simple graphic illustrating the concept of a consensus in blockchain

🧭 Lesson Overview: Blockchain Consensus Explained

This lesson dives into one of the most fundamental concepts in blockchain technology: consensus algorithms. You'll explore how decentralized networks like Bitcoin and Ethereum reach a shared agreement on a valid transaction history without a central authority.

You’ll break down the two key pillars of a consensus mechanism:

Sybil Resistance: Learn how networks prevent fake identities from gaining control, through methods like Proof of Work (PoW), Proof of Stake (PoS), and Proof of Authority (PoA).

Chain Selection: Understand the rules that determine which version of a blockchain is accepted as the canonical one when conflicts arise.

Through real-world examples from Bitcoin, Ethereum, and Solana, you will compare these mechanisms in terms of their trade-offs, including energy use, decentralization, and scalability. By the end of this lesson, you will be equipped to evaluate different blockchain designs and apply your knowledge to broader Web3 applications.

📚 Learning Steps: Your Path to Technical Fluency

  1. ✅ Master the Vocabulary: Familiarize yourself with all essential blockchain terms so you can talk confidently about them.

  2. 📖 Go Hands-on: Complete the reading assignment to reinforce your understanding of the core concepts.

  3. 📝 Test Your Knowledge: Take the comprehension quiz to solidify your learning and ensure you're ready for the next lesson.

🧠 Essential Blockchain Vocabulary

Before diving deeper into consensus algorithms, build your Web3 vocabulary with our essential terms. These definitions and real-world analogies are designed to help you create a mental model of how blockchain concepts work. By mastering this technical terminology, you’ll be better equipped to understand the technologies discussed in this lesson.

Each term has been selected to support your understanding of consensus algorithms at both a conceptual and practical level.

Canonical

Casper FFG

Deterministic

Epoch

ETH

Finality

GHOST

Hash

Scalability

Slashing

SOL

Staking

Sybil resistance

Throughput

Timestamp

📘 Challenge Yourself

Ready to go hands-on? Complete the reading assignment to reinforce this lesson's concepts. Then, take the short quiz to test your technical fluency.

📝 Quiz: Test Your Blockchain Knowledge

Ready to put your skills to the test? Take this short quiz to test your understanding of the lesson's core concepts. Solidify your knowledge before moving on to the next topic in your learning path.

1. Which of the following is a Sybil resistance mechanism used in Bitcoin?

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