# How blockchain works, step by step > From pressing send in a wallet to a payment you can treat as final, a transaction passes through six stages. This is each of them, and why the process is safe without a central authority. Updated 2026-10-08 · Payaries · https://www.payaries.com/blog/how-blockchain-works ## A transaction's journey If you haven't yet, read [what a blockchain is](https://www.payaries.com/blog/what-is-blockchain) first. This guide follows a single payment through the network, from creation to finality. > **Diagram — The six stages between sending a transaction and being able to rely on it..** 1. Your wallet creates and signs the transaction. 2. Network nodes receive it, verify the signature and that the funds exist. 3. It waits in the mempool with other valid transactions. 4. A validator or miner bundles queued transactions into a block. 5. The whole network checks and agrees on the block (consensus). 6. Each further block on top adds a confirmation. ## 1. Signing: proof it is yours A transaction says, in effect, "move this amount from my address to that address." The wallet signs it with the sender's private key. Anyone can check the signature against the sender's public key, but nobody can forge one without the private key — and the key itself is never revealed. ## 2–3. Verification and the mempool The signed transaction is broadcast to nearby nodes, which pass it on. Each node independently checks that the signature is valid, that the sender really has the funds, and that the same funds aren't being spent twice. Invalid transactions are dropped immediately. Valid ones wait in a pool of pending transactions, the mempool. When a network is busy, senders attach a higher fee to get picked sooner — the network fee, paid in the chain's native coin (ETH, BNB, TRX and so on). See [how Payaries's gas station handles it](https://www.payaries.com/blog/gas-station-network-fees). ## 4–5. Building a block and reaching consensus Someone has to decide which pending transactions go into the next block, and in what order, so that every node ends up with the same history. That is the job of the consensus mechanism. The two main designs: | | Proof of work | Proof of stake | |---|---|---| | Who proposes a block | Miners racing to solve a computational puzzle | A validator selected in proportion to the coins they have locked up as a stake | | What makes cheating costly | The electricity and hardware spent | The staked coins can be forfeited for dishonest behaviour | | Used by | Bitcoin | Ethereum (since 2022), BNB Smart Chain, Polygon and others; Tron uses a delegated variant | | Typical block time | About 10 minutes on Bitcoin | Seconds — about 12 on Ethereum, about 3 on Tron | Either way, the proposed block is broadcast, other nodes verify every transaction inside it and its link to the previous block, and the chain grows by one. Honest nodes always follow the valid chain with the most accumulated work or backing. ## 6. Confirmations and finality Once your transaction is in a block, it has one confirmation. Each block added after it is another. Occasionally two blocks are produced at nearly the same time and the network briefly disagrees; one branch is later abandoned and its transactions return to the mempool. That is why a single confirmation is not proof of payment on every chain, and why the number needed varies by network. Deeper blocks are exponentially harder to replace. Merchants therefore wait for a chain-specific number of confirmations before treating a payment as final — the logic behind [crypto payment confirmations](https://www.payaries.com/guides/crypto-payment-confirmations). ## Why you can trust it without trusting anyone - **Signatures** make forging a payment impractical. - **Hash links** make rewriting history detectable. - **Independent verification** means each node checks everything itself, rather than taking someone's word. - **Economic cost** — work or staked coins — makes attacking the network more expensive than it is worth on large chains. > **Where the risk really is.** Small chains with little work or stake behind them are easier to attack, and smart-contract bugs and stolen keys are far more common than broken cryptography. Safe payments depend on choosing mature networks and waiting for sufficient confirmations. ## What this means for accepting payments A merchant doesn't need to run nodes or watch mempools. A [crypto payment gateway](https://www.payaries.com/blog/what-is-a-crypto-payment-gateway) does that work across several chains and tells your backend when a payment has reached its required confirmations. ## Questions **How does a blockchain work, briefly?** A signed transaction is broadcast, checked by nodes, collected into a block by a validator or miner, agreed by the network and added to the chain. Each later block adds a confirmation. **What is the difference between proof of work and proof of stake?** Proof of work secures a chain with computing effort, as Bitcoin does. Proof of stake secures it with coins that validators lock up and can lose if they cheat, as on Ethereum today. **How long does a blockchain transaction take?** From seconds to tens of minutes, depending on the network, its current congestion and how many confirmations you wait for. Bitcoin blocks average around ten minutes; many other chains produce blocks in seconds. **Why do transactions need multiple confirmations?** Because a block can occasionally be replaced shortly after it appears. Each additional block on top makes reversal less likely, so more confirmations means more certainty. ## Try it See a payment confirm in real time: [Payaries — www.payaries.com](https://www.payaries.com/signup). Payaries is a multi-chain crypto payment gateway — https://www.payaries.com ## Keep reading - https://www.payaries.com/blog/what-is-blockchain — What is blockchain? A simple explanation - https://www.payaries.com/guides/crypto-payment-confirmations — Crypto payment confirmations, explained for merchants - https://www.payaries.com/guides/how-a-crypto-payment-gateway-works — How a crypto payment gateway works, from invoice to settlement - https://www.payaries.com/blog/usdt-trc20-vs-erc20-vs-bep20 — USDT on TRC-20, ERC-20 and BEP-20: what changes for a merchant - https://www.payaries.com/blog/what-is-crypto — What is crypto? Explained simply - https://www.payaries.com/blog/what-is-cryptocurrency — What is cryptocurrency? A plain-English guide - https://www.payaries.com/blog/what-is-a-crypto-payment-gateway — What is a crypto payment gateway?