Mining Fees, Block Data, Block Headers, and Proof-of-Work
Now that we have some background on what the mining process does for Bitcoin, let's cover the specifics. This chapter covers the technical process, including mining fees, block data, block headers, and Proof-of-Work.
Successfully Mining the Block
As we saw earlier, Jing's node has constructed a candidate block and prepared it for mining. Jing has several hardware mining rigs with application-specific integrated circuits, where hundreds of thousands of integrated circuits run the SHA256 algorithm in parallel at incredible speeds. Many of these specialized machines are connected to his mining node over USB or a local area network. Next, the mining node running on Jing's desktop transmits the block header to his mining hardware, which starts testing trillions of nonces per second. Because the nonce is only 32 bits, after exhausting all the nonce possibilities (about 4 billion), the mining hardware changes the block header (adjusting the coinbase extra nonce space or timestamp) and resets the nonce counter, testing new combinations.
Almost 11 minutes after starting to mine block 277,316, one of the hardware mining machines finds a solution and sends it back to the mining node.
When inserted into the block header, the nonce 924,591,752 produces a block hash of:
0000000000000001b6b9a13b095e96db41c4a928b97ef2d944a9b31b2cc7bdc4
which is less than the target:
0000000000000003A30C00000000000000000000000000000000000000000000
Immediately, Jing's mining node transmits the block to all its peers. They receive, validate, and then propagate the new block. As the block ripples out across the network, each node adds it to its own copy of the blockchain, extending it to a new height of 277,316 blocks. As mining nodes receive and validate the block, they abandon their efforts to find a block at the same height and immediately start computing the next block in the chain, using Jing's block as the "parent". By building on top of Jing's newly discovered block, the other miners are essentially "voting" with their mining power and endorsing Jing's block and the chain it extends.
In the next section, we'll look at the process each node uses to validate a block and select the longest chain, creating the consensus that forms the decentralized blockchain.