Bitcoin transactions are verified through a process called mining. Mining is the process of verifying and adding transaction records to the Bitcoin blockchain, a distributed public ledger of all past transactions.

When a user sends a transaction, the transaction is broadcast to the Bitcoin network and collected by miners in a process known as mining. These miners then use specialized software to validate and confirm the transaction. This involves solving a cryptographic puzzle; if the miner solves the puzzle correctly, they receive a reward in the form of newly created bitcoins.

Once the transaction is validated, it is added to the blockchain and is marked as confirmed. The entire Bitcoin blockchain is constantly monitored and updated by the miners, and the transaction will be permanently recorded and visible to all other users once it is confirmed. This ensures that no one can double-spend or tamper with the transaction in any way.

By verifying each transaction, miners also ensure the security of the Bitcoin network by preventing any form of double-spending. The process of mining also helps to decentralize the network, as it makes it more difficult for any single entity to control or manipulate the network. As more miners join the network, it becomes more secure and reliable.