Blockchain Platforms Overview

Core principles, consensus mechanisms, and key innovations of major blockchain platforms.

Bitcoin (BTC)

Core Principles

• Digital gold: Store of value, not programmable
• Decentralization: ~15,000 full nodes worldwide
• Security: Most secure blockchain (highest hash rate)
• Simplicity: Intentionally limited functionality

Consensus

• Proof of Work (PoW): SHA-256 mining
• Block time: ~10 minutes
• Block size: 1-4 MB (with SegWit)
• Finality: Probabilistic (~6 confirmations)

Key Innovations

• UTXO model: Unspent Transaction Outputs
• Script: Stack-based, non-Turing complete
• Lightning Network: Layer 2 for instant payments
• Taproot: Privacy + smart contract improvements

Use Cases

• Store of value
• Censorship-resistant payments
• Final settlement layer

Ethereum (ETH)

Core Principles

• World computer: Decentralized computation platform
• Smart contracts: Turing-complete programs
• EVM: Ethereum Virtual Machine
• Account model: Not UTXO

Consensus

• Proof of Stake (PoS): Since "The Merge" (2022)
• Block time: ~12 seconds
• Finality: ~15 minutes (2 epochs)
• Validators: 32 ETH stake required

Key Innovations

• Smart contracts: Solidity language
• ERC standards: ERC-20 (tokens), ERC-721 (NFTs)
• Layer 2: Rollups (Optimistic, ZK)
• Sharding: Future scalability (Danksharding)

Architecture

Use Cases

• DeFi (Decentralized Finance)
• NFTs and digital assets
• DAOs (Decentralized Autonomous Organizations)
• General-purpose smart contracts

Cosmos (ATOM)

Core Principles

• Internet of Blockchains: Interconnected chains
• Sovereignty: Each chain controls own governance
• Interoperability: IBC (Inter-Blockchain Communication)
• Modularity: Cosmos SDK for custom chains

Consensus

• Tendermint BFT: Byzantine Fault Tolerant
• Block time: ~6 seconds
• Finality: Instant (single block)
• Validators: Delegated Proof of Stake

Key Innovations

• IBC Protocol: Cross-chain communication
• Cosmos SDK: Framework for building blockchains
• Hub-and-Zone model: Cosmos Hub connects zones
• Shared security: Interchain Security

Architecture

Use Cases

• Application-specific blockchains
• Cross-chain DeFi
• Sovereign chains with interoperability

Polkadot (DOT)

Core Principles

• Shared security: All parachains secured by relay chain
• Heterogeneous sharding: Different chains, different purposes
• Cross-chain messaging: XCM (Cross-Consensus Message)
• Governance: On-chain, forkless upgrades

Consensus

• GRANDPA + BABE: Finality + block production
• Block time: ~6 seconds
• Finality: 1-2 blocks (~12 seconds)
• Validators: Nominated Proof of Stake (NPoS)

Key Innovations

• Relay Chain: Central security hub
• Parachains: Parallel chains with shared security
• Parathreads: Pay-per-block parachains
• Substrate: Framework for building blockchains

Architecture

Use Cases

• Specialized blockchains with shared security
• Cross-chain applications
• Scalable multi-chain ecosystems

Solana (SOL)

Core Principles

• High performance: 65,000+ TPS theoretical
• Low cost: Fractions of a cent per transaction
• Proof of History: Novel time-keeping mechanism
• Single global state: No sharding

Consensus

• Proof of History + PoS: Hybrid approach
• Block time: ~400ms
• Finality: ~13 seconds
• Validators: Permissionless PoS

Key Innovations

• Proof of History (PoH): Verifiable delay function for time
• Sealevel: Parallel smart contract runtime
• Gulf Stream: Mempool-less transaction forwarding
• Turbine: Block propagation protocol

Architecture

Use Cases

• High-frequency trading
• Gaming and NFTs
• Real-time applications
• DeFi with low fees

Cardano (ADA)

Core Principles

• Research-driven: Peer-reviewed academic approach
• Formal methods: Mathematical verification
• Layered architecture: Settlement + Computation
• Sustainability: Treasury system for funding

Consensus

• Ouroboros PoS: Provably secure
• Block time: ~20 seconds
• Finality: Probabilistic (~15 blocks)
• Stake pools: Delegated staking

Key Innovations

• EUTXO model: Extended UTXO with smart contracts
• Plutus: Haskell-based smart contracts
• Hydra: Layer 2 state channels
• Catalyst: Decentralized governance

Architecture

Use Cases

• Identity and credentials
• Supply chain tracking
• DeFi with formal verification
• Developing nations (financial inclusion)

Comparison Table

Common Concepts

Consensus Mechanisms

• PoW: Energy-intensive, secure, slow
• PoS: Energy-efficient, faster, economic security
• BFT: Instant finality, requires known validators
• PoH: Novel time-keeping for ordering

Scalability Approaches

• Layer 2: Lightning, Rollups, State Channels
• Sharding: Divide network into parallel chains
• Sidechains: Separate chains with bridges
• Parachains: Shared security model

Finality Types

• Probabilistic: Becomes more certain over time (Bitcoin)
• Instant: Single block confirmation (Tendermint)
• Economic: Slashing for misbehavior (PoS)

Notes

• Blockchain trilemma: Decentralization, Security, Scalability - pick 2
• Layer 1 vs Layer 2: Base chain vs scaling solution
• EVM compatibility: Many chains support Ethereum contracts
• Interoperability: Growing focus on cross-chain communication

Gotchas/Warnings

• ⚠️ Finality: Understand probabilistic vs instant finality
• ⚠️ MEV: Miner/Validator Extractable Value is an issue
• ⚠️ Bridge risks: Cross-chain bridges are attack vectors
• ⚠️ Centralization: Many "decentralized" chains have few validators