Module 6 · Ethereum & Shared Applications / 6.3
Follow an instruction through Ethereum.
An account, a request, and the work needed to update the record.
You open a wallet and see a token balance. You press send. The wallet asks for a fee in ETH.
Why another asset? And what, exactly, is the network doing with your instruction?
Follow one request. The same path will help you understand a payment, a token approval, and a swap.
The account is not the app.
An Ethereum address identifies an account in the shared record. Your wallet is software that helps you view accounts and authorize actions. Changing wallet software does not move the account to a different blockchain.
Ethereum tracks account balances and other current data. The collection of balances, contract code, and stored values is called its state. A transaction requests a change to that state.
Ordinary key-controlled accounts can initiate signed transactions. A contract account follows code when called during execution. It does not wake up because a calendar date arrives; some submitted transaction must trigger the work.
The Ethereum Virtual Machine, or EVM, defines how that work runs. Full validating nodes can independently execute the same valid instruction and check the same result. Not every device that reads a balance is a full validating node.
Every copy starts at five. This is a simplified deterministic state update.
Wallets can wrap these steps
Smart accounts, transaction relays, and account delegation can change the user experience. A service may sponsor fees, and a wallet may bundle actions. That does not remove the underlying execution rules or mean any site can spend from an account without the required authorization.
A transaction’s nonce helps enforce its order and prevent replay within the account’s transaction sequence. A token balance usually lives in the token contract’s storage, distinct from the account’s native ETH balance.
Work units and the price of work.
Gas measures computational work. A gas price expresses what each unit of work costs. The transaction fee depends on gas used multiplied by the effective price per unit.
For a made-up machine, suppose an instruction uses four work units priced at three fee units each. It costs twelve fee units. Offering a larger work limit does not mean every unused unit is charged.
On Ethereum, fees are denominated in ETH. The base-fee portion is burned, meaning it is removed from supply. A priority fee rewards the block proposer. Network demand changes the base fee, so a quote is not a permanent price.
Holding another token does not by itself fund an ordinary Ethereum transaction’s fee. Some wallets arrange sponsorship, but a user should verify the fee asset and network shown in the actual request.
Execution finishes. Unused work allowance is not charged in this simplified model.
Fictional work units and prices. Not an Ethereum gas estimate.
A common interface is useful, not a guarantee.
Token standards let different applications recognize a common set of functions. ERC-20 covers interchangeable units, such as a balance you can divide. ERC-721 identifies distinct tokens, each with its own identifier.
A standard makes integration easier. It does not mean every wallet supports a token, that the token has legal rights, or that its contract is safe. A token on Ethereum uses Ethereum’s transaction ordering while retaining its own contract risks.
Approving a token allowance can let a named spender move tokens later, subject to that allowance. It is a different instruction from transferring tokens now. That difference matters when the wallet asks you to sign.
More room through layers.
A rollup handles execution outside Ethereum’s base layer and submits information that lets Ethereum help enforce its results. Optimistic rollups use a system of challenges. Validity rollups use proofs that execution followed the rules.
Both still need accessible data and working contracts. A sequencer may control transaction inclusion temporarily. Upgrade keys, proof systems, withdrawal delays, and emergency exits vary by rollup. “Uses Ethereum” does not make every system equally secure.
A bridge connects assets or messages across systems. Some lock assets and represent claims elsewhere. Others use different transfer designs. The connection adds its own verification and control assumptions.
A matching address shape is not enough: the network and asset must match the destination. Layers can reduce fees, but choosing the wrong network can still strand a transfer.
Each layer has its own operators, controls, and failure conditions. This simplified view omits the RPC connection.
The idea to keep
A wallet requests an authorized state change. Nodes check execution, gas pays for work, and the chosen network determines which records and rules apply.