Now that we know how wallets work, it is time to understand what actually happens when someone sends Bitcoin. To the outside world, a transaction may look as simple as Alice scanning a QR code and sending Bob some coins, but beneath that simple interface lies a fascinating process that makes Bitcoin both secure and decentralized.

When Alice decides to send one Bitcoin to Bob, she opens her wallet and enters Bob’s public address. This address is like Bob’s mailbox on the blockchain — anyone can see it and send coins to it, but only Bob, with his private key, can unlock the coins once they arrive. Alice’s wallet then creates a digital message that says, in effect, “I am sending one Bitcoin from my account to Bob’s account.” But how does the network know this is really Alice and not someone pretending to be her? This is where her private key comes in.

The wallet takes Alice’s private key and uses it to generate a digital signature for the transaction. This signature is unique: it proves to the entire network that Alice is the rightful owner of the Bitcoin being spent. Crucially, the private key itself is never revealed. Everyone can check the signature using Alice’s public key, but no one can reverse-engineer it to discover her private key. This allows Alice to prove ownership without ever exposing her secret, a remarkable achievement of modern cryptography.

Once the transaction is signed, Alice’s wallet broadcasts it to the Bitcoin network. Thousands of nodes scattered around the world receive the message and immediately get to work verifying it. They check that Alice really has one Bitcoin available, that she has not already spent it elsewhere, and that the signature is valid. Only after all these conditions are satisfied is the transaction considered valid and ready to be included in the blockchain.

But the transaction does not enter the blockchain right away. First, it waits in a holding area called the mempool — short for “memory pool.” Think of the mempool as a waiting room at the airport. Transactions line up there until miners, who act like airlines, select which ones to take on board. Since miners are rewarded not only with newly created Bitcoin but also with transaction fees, they prioritize the transactions that offer higher fees. This is why sometimes your Bitcoin transaction is confirmed quickly and cheaply, while other times it takes longer or costs more depending on how busy the network is.

Once a miner selects Alice’s transaction and includes it in a block, the race begins to solve the mathematical puzzle that seals the block. The first miner to solve it earns the right to add the block to the blockchain and broadcasts the new block to the entire network. Instantly, every node updates its copy of the blockchain, and Alice’s payment to Bob becomes a permanent part of Bitcoin’s history. From this moment forward, Bob can see the transaction in his wallet, and the Bitcoin is his to spend.

At first, a transaction is considered “unconfirmed” because it is included in only one block. Over time, as more blocks are added on top, the confirmation becomes stronger and harder to reverse. This is why exchanges or merchants sometimes require several confirmations before they consider a payment final. It is like cement drying: after a few minutes, it seems solid, but after an hour, it is permanent.

What is most remarkable is that this entire process happens without a central authority. No bank approves the transfer, no government signs off, and no company manages the ledger. Instead, the rules of the system — wallets, keys, signatures, nodes, miners, and the blockchain — ensure that Alice’s payment to Bob is secure, transparent, and irreversible.

In this way, sending Bitcoin is both simple and profound. From the user’s perspective, it is just a few taps on a phone. Behind the scenes, however, a global network of computers collaborates to verify, secure, and record the transfer in a way that no single actor controls. It is a process that redefines trust, shifting it away from institutions and placing it instead in code, mathematics, and open consensus.

To understand how Bitcoin transactions are sent is to appreciate why the system is so powerful. It takes the ordinary act of making a payment and transforms it into something extraordinary: a peer-to-peer exchange of value that needs no permission, no middleman, and no gatekeeper. In a world where money has always relied on central authorities, Bitcoin’s method of sending transactions is nothing short of revolutionary.