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Bitcoin (BTC)
BitcoinBTC is the first cryptocurrency, launched in 2009. It uses the UTXO model (balances are sets of spendable outputs), Proof of Work with ~10-minute blocks, and a hard supply cap of 21 million coins. New issuance halves roughly every four years (the halving), making the supply schedule fully predictable. Its design is deliberately simple: it optimizes for security, decentralization, and scarcity — not programmability or throughput.
- Ledger model: UTXO.
- Consensus: Proof of Work.
- Fee asset: BTC.
- Supply: capped at 21M; issuance halves ~every 4 years.
- L2: the for fast, cheap payments.
Proponents call Bitcoin "digital gold" because its fixed supply and censorship resistance make it a candidate store of value. Critics note its volatility, energy use, and the fact that gold itself has historically been a mediocre store of value in real terms. The honest framing: Bitcoin is a new monetary asset whose long-term role is still being discovered.
Ethereum (ETH)
EthereumETH launched in 2015 as the first general-purpose smart-contract blockchain. It uses the account model (balances stored per account, like a bank) and, since the Merge in 2022, Proof of Stake. Its native token, ETH, is the fee asset: every computation and storage operation costs gas paid in ETH. Smart contracts make Ethereum programmable — tokens (ERC-20), NFTs (ERC-721), DeFi protocols, and most L2s all run on it.
- Ledger model: account-based.
- Consensus: Proof of Stake (post-Merge).
- Fee asset: ETH.
- Supply: no hard cap; issuance is offset partly by fee burning (EIP-1559).
- L2s: a large family of rollups — Arbitrum, Optimism, Base, zkSync, Starknet, Linea, and more.