Genesis Block Explained

Genesis Block Explained

The genesis block is the first block in any blockchain-based protocol. It is the foundation on which additional blocks are sequentially added to form a chain of blocks, resulting in the term, blockchain being coined.

The genesis block is also referred to as block zero. The second block to be added on top of block zero would then be referred to as block number 1. The number used to refer to the ordering of blocks is known as the block height number. The block height number is always a positive integer greater than zero.

For example, at the time of writing, the current block height number of the Bitcoin blockchain is 555,958. What this means is, including the genesis block, there have been a total of 555,958 blocks constructed since Bitcoin’s launch in 2009 by unknown develop, Satoshi Nakamoto. With a block generation time of 10 minutes, this means that new blocks are added to the Bitcoin blockchain roughly once every 10 minutes.

Bitcoin Genesis Block – Coinbase Transaction

Included with every block on the Bitcoin network is what is known as a coinbase transaction. A coinbase transaction is the first transaction a miner places in a block constructed by them; it is a transaction rewarding the miner in bitcoins for successfully creating a block to be relayed to the network. When Satoshi constructed the genesis block, the reward for doing so was 50 bitcoins; these 50 bitcoins were sent to the bitcoin address: 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa, thought to be controlled by Nakamoto. In the coinbase data of the transaction, which allowed for text to be included by a miner, Satoshi left the following message:

“The Times 03/Jan/2009 Chancellor on brink of second bailout for banks”

It is suspected that this text was included by Satoshi as proof that the genesis block had been generated on January 3rd, 2009. Information providing data on the genesis’ block construction can be found on This includes information such as: number of transactions contained in the block, the timestamp, the block difficulty and the block height.

Genesis Block – Block data

Some of the block data of the genesis block includes:

  • Number of transactions: 1
  • Transaction fee: $0.00
  • Block height: 0
  • Timestamp: 03/02/3009, 18:15
  • Nonce: 208393
  • Block difficulty: 1

Number of transactions – Remembering that blocks contain transactions that have occurred on the Bitcoin network, there exists only one transaction in the genesis block. No other transactions besides the coinbase transaction in the genesis block was mined by Satoshi.

Transaction fee – Typically on the bitcoin network, users pay a transaction fee to miners in order to have their transactions confirmed by the network; the average transaction fee currently stands at $0.17. No transaction fee was taken by Satoshi when constructing the genesis block because there was no transaction to take a fee from. Fees cannot be extracted from the coinbase transaction as it is a transaction rewarding the miner for creating the block.

Block height – As previously mentioned, the genesis block has a block height of zero and provides the foundation on which additional blocks are then added.

Timestamp – The time at which the miner started hashing the block header.

Nonce – The nonce is an arbitrary variable that a miner continually changes in order to be awarded the right to add a block to the blockchain. In this case, the nonce that Satoshi used was variable 208393.

Block difficulty – The difficulty is a measure of how hard it is for a miner to find the nonce value that successfully permits them to add a block to the blockchain. When Satoshi was generating the genesis block, the difficulty of the Bitcoin network stood at a value of “1”. This in contrast to the difficulty today which currently stands at 5,106,422,924,659.

Bitcoin Full Nodes

Bitcoin full nodes are responsible for validating unconfirmed transaction as well as recently-mined blocks. However, before a node can fulfil those responsibilities, it must download and validate all blocks starting from block number 1 up until the current height of the Bitcoin blockchain – this is known as the Initial Block Download (IBD). The genesis block, block number zero, is hardcoded into Bitcoin full node client and thus does not need to be downloaded.