Web3 & DApp Development Fundamentals · Lesson

Transaction Lifecycle

From signing to mining.

Transaction Lifecycle is a free Web3 & DApp Development Fundamentals lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Web3 & DApp Development Fundamentals learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

From Click to Confirmation

When you send a transaction, a lot happens behind the scenes before it becomes permanent.

This lesson walks through the full transaction lifecycle, from signing to inclusion in a block.

Step 1: Building the Transaction

Your wallet assembles a transaction object containing the recipient, value, data, gas settings, and a nonce.

tx = {
  to:    0xRecipient...,
  value: 1000000000000000000, // 1 ETH
  nonce: 7,
  gasLimit: 21000,
  maxFeePerGas: 30 gwei
}

Step 2: Signing

The wallet signs the transaction with your private key, producing a digital signature.

The signature proves you authorized it without ever revealing your private key. Anyone can verify it using your public address.

Step 3: Broadcasting

The signed transaction is broadcast to a node, which validates it and gossips it to peers across the network.

Within seconds, nodes everywhere know about your pending transaction.

Step 4: The Mempool

Pending transactions wait in the mempool (memory pool) — a holding area for transactions not yet included in a block.

Validators pick from the mempool when building the next block.

mempool (pending):
  tx A  (tip: 5 gwei)
  tx B  (tip: 2 gwei)
  tx C  (tip: 8 gwei)  <- picked first

Step 5: Selection by a Validator

A validator building a block selects transactions, usually favoring higher fee tips for more revenue.

Paying a higher tip can speed up inclusion, especially when the network is congested.

Step 6: Execution

The validator executes the transaction on the EVM, updating account balances and contract state, consuming gas as it goes.

If it runs out of gas or hits an error, it reverts — but the gas spent is still consumed.

Step 7: Inclusion in a Block

The executed transaction is packed into a new block along with others. The block is proposed and attested to by validators.

At this point your transaction has one confirmation.

Step 8: Confirmations and Finality

As more blocks build on top, your transaction gains confirmations. On Ethereum PoS, it eventually becomes finalized and irreversible.

Now the transfer or contract call is permanently settled.

Receipts

After execution, the network produces a transaction receipt recording status (success or revert), gas used, and any emitted events (logs).

Apps read receipts to confirm what actually happened on-chain.

receipt = {
  status: 1,        // 1 = success, 0 = revert
  gasUsed: 21000,
  blockNumber: 18250431,
  logs: [ ... ]
}

Putting It Together

A transaction is built, signed, broadcast, queued in the mempool, selected and executed by a validator, included in a block, and finally confirmed and finalized.

A receipt records the outcome.

Quick Check

Test your understanding of the lifecycle.

Recap: Transaction Lifecycle

You learned the stages:

Build and sign with the private key
Broadcast to the network
Wait in the mempool
Selected, executed, and included in a block
Confirmed and finalized, with a receipt

Next: gas limits and fees.

Frequently asked questions

Is the “Transaction Lifecycle” lesson free?

Yes — the full text of “Transaction Lifecycle” is free to read here on the web, and the Web3 & DApp Development Fundamentals course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Web3 & DApp Development Fundamentals course, upgrade to CoddyKit PRO.

What will I learn in “Transaction Lifecycle”?

From signing to mining. You practise Web3 & DApp Development Fundamentals with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Web3 & DApp Development Fundamentals?

No prior experience is required. Web3 & DApp Development Fundamentals on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Transaction Lifecycle” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Web3 & DApp Development Fundamentals lesson?

Yes. Every Web3 & DApp Development Fundamentals lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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