What is the Bitcoin genesis block?

The Bitcoin genesis block is the very first "block" of transactions ever confirmed on the Bitcoin blockchain after launching.

It's a good time to check out the Genesis Block of Bitcoin.

👆🏼 How many properties do you recognize at this point?

The number of confirmations is the number of blocks since the genesis block. Since the genesis block is the first block, this is also the block height of the blockchain!

It's interesting that if you look at the nonce of the genesis block, it's 2,083,236,893. If you take a look at a more recent block, 632900 for example, you'll see that the nonce is actually much lower. Why is that? Isn't the difficulty supposed to be getting harder as the network grows? 🤔

It turns out that the block nonce is actually a 32-bit field, and 2 ** 32 is 4,294,967,296, so that is the max size of a nonce. What happens when the miner reaches this point? They can change anything else in the block header to also increase the randomness. Other properties include:

  • Software Version - Tracks Bitcoin software upgrades
  • Previous Block Hash - Hash of the block before this one
  • Merkle Root - We haven't gone over this yet, its a hash that represent all the transactions!
  • Timestamp - Approximate time (less than two hours in the future according to consensus rules)
  • Target - Difficulty Target that dictates how small the Proof Of Work must be

👆🏼 As you can imagine by looking at these properties, it was initially the timestamp that the miners fiddled with when they needed to restart their search for a valid Proof-of-Work. Beyond that, they can start to change the script of the coinbase transaction which gives them additional nonce space.

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