In short
- Ethereum combines account state, smart-contract execution and proof-of-stake consensus.
- Gas meters computation and fees; ETH is the native asset used in these mechanisms.
- Execution and consensus solve different validation problems.
- Contract, wallet, oracle, bridge and governance risks remain.
After this lesson you can
- Explain Ethereum accounts, transactions, smart contracts and gas
- Describe the distinct roles of execution and proof-of-stake consensus
- Identify contract, key, fee, validator and application risks
Shared computation with paid execution
Ethereum maintains account and contract state. A user signs a transaction that can transfer ETH or call a smart contract, a program stored at an address. Execution consumes gas, which meters computational work; fees discourage unbounded resource use. Execution clients apply state transitions, while consensus clients and proof-of-stake validators agree on block history and finality. Smart contracts execute code as deployed; that does not mean the code is correct, upgrade-free or legally complete.
Key point: Separate ETH the asset, EVM execution, gas accounting, contract logic and consensus security.
Execution and consensus
| Execution layer | Consensus layer | |
|---|---|---|
| Question | What state transition does this transaction produce? | Which blocks form the accepted chain? |
| Participants | Execution clients re-run transactions | Validators propose and attest |
| Failure focus | Contract bugs, invalid state, gas behavior | Validator faults, finality and fork choice |
Call a smart contract
A wallet asks a user to approve a token-spending transaction.
- Verify network, destination contract and requested function.
- Distinguish a limited transfer from a broad allowance or privileged call.
- Estimate gas and recognize the transaction can fail while consuming fees.
- Treat verified source matching as useful evidence, not proof the logic is safe or economically sound.
Common trap: interpreting trustless as riskless
Removing one intermediary can replace that dependency with contract code, validators, bridges, oracles, governance keys and wallet security. Transactions and contract interactions may be difficult to reverse. Trust assumptions are redistributed and made more explicit; they do not disappear.
Practise what you just read
Take this lesson's quiz and review cards in the app, then try the idea with virtual money in paper trading. Free account, no card.
Education only, not investment advice. Examples are illustrative. Read the full disclaimer