This is the part where the safety nets come down. No pretests, no warm-up analogies, no “guess before reading” — just the course, asking whether any of it stuck. Everything you need, the previous seven lessons already taught you. Read each option twice; the trap is usually the one that’s 90% right.
How this exam works
This is a graded exam. Questions come one at a time. Once you submit an answer it is final — there is no going back, no second try, and a wrong answer simply fails that question. Your score stays hidden until the end, where you need 70% to pass. Read every option twice before you commit.
Someone says 'Ethereum is just Bitcoin with a different logo.' What is the sharpest correction?
Select an answer to continue.
Course Recap
Big picture
The whole Ethereum machine
- Ethereum, end to end
- What Ethereum is
- Programmable world computer, not just money
- ETH fuels computation; smart contracts run on it
- 1 ETH = 1e9 gwei = 1e18 wei
- No supply cap; base fee burned by EIP-1559
- The EVM
- World state: balances, nonces, code, storage
- Deterministic state transitions
- Every node re-executes to agree
- Runs compiled bytecode, Turing-complete
- Accounts vs UTXO
- EOA controlled by a key
- Contract account controlled by code
- Per-account running balance, not unspent outputs
- Nonce orders txs and blocks replay
- Gas & fees
- Gas = work; gas limit = your ceiling
- Fee = gas used × gas price
- EIP-1559: base fee burned + priority tip
- Fees spike when block space demand surges
- Contracts & tokens
- Code at an address, runs on call
- Immutable: trust vs unpatchable bugs
- Token = balance mapping in one contract
- ERC-20 fungible vs ERC-721 NFT
- approve/allowance; standards = interop
- Proof-of-stake
- 32 ETH bonded as slashable collateral
- Stake-weighted proposer selection
- Propose vs attest each slot
- Finality is economic irreversibility
- The Merge: ~99.9% energy cut
- Layer-2 rollups
- Execute off-chain, post data on-chain
- Amortized cost per user
- Optimistic: fraud proof, ~7-day window
- ZK: validity proof, fast finality
- Rollup inherits L1 security; sidechain does not
- What Ethereum is
Key Takeaways
What to remember
- Ethereum is a programmable world computer — not Bitcoin with a new logo. ETH (1 ETH = 10^18 wei = 10^9 gwei) fuels computation, there’s no supply cap, and EIP-1559 burns the base fee.
- The EVM runs deterministic bytecode over a shared world state — balances, nonces, code, and storage. Every node re-executes each block to reach byte-identical agreement.
- Ethereum is account-based, not UTXO — EOAs are key-controlled, contract accounts are code-controlled, balances run up and down, and the nonce orders transactions and blocks replay.
- Fees are gas used × gas price — gas measures work, the gas limit caps it, the base fee is burned and the priority tip pays validators, and fees spike when demand for scarce block space surges.
- Smart contracts are immutable code at an address — tokens are balance mappings in a single contract; ERC-20 is fungible, ERC-721 is NFTs, approve sets an allowance, and shared standards buy interoperability.
- Proof-of-stake secures Ethereum — 32 ETH is slashable collateral, proposers are picked by stake-weighted randomness, committees attest, finality is economic irreversibility, and The Merge cut energy use ~99.9%.
- Rollups scale Ethereum — they execute off-chain and post data to L1, amortizing cost per user. Optimistic rollups use fraud proofs with a ~7-day window; ZK rollups use validity proofs for fast finality. A sidechain, with its own consensus, isn’t a rollup.