## How do you make a Genesis block?

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What is involved in creating a genesis block? What makes it different from the other blocks in the chain.

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There is only one (Bitcoin) chain, and the Genesis Block is the first block in that chain.

This block was created by Satoshi Nakamoto as the first link in the blockchain. It is hard-coded into the refernce Bitcoin client. To create it, it was "mined" like every other block, except it was at the minimum difficulty level, and contained arbitrary data.

The following quote from The Financial Times is embedded in the block's binary data

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

This serves to prove it was generated on or after January 3rd 2009, as well as a political statement regarding the global economy.

4Today I learned. – Colin Dean – 2013-04-15T04:12:42.620

Even though the Genesis block (almost) satisfies all rules that other blocks have to satisfy (and even more, see https://bitcointalk.org/index.php?topic=172009.0), it is not actually validated by full nodes. It's just a hardcoded starting point, and it would actually have worked just as well if it did not carry any proof of work.

– Pieter Wuille – 2013-04-15T09:13:09.910

@PieterWuille, Do you mean that any hash could qualify as the genesis block and we don't need zeros in front of it? – Pacerier – 2014-05-25T05:51:44.133

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The genesis block is really nothing more than a block that doesn't have a previous block. Creating a new genesis block only involves setting the previous hash part of the block to all zeroes. Because it doesn't have a previous block, it's automatically the first block in the chain, and creating a new genesis block means that you create a new block chain.

There are actually four 'official' genesis blocks out there, one for the main Bitcoin chain, and there have been three 'test nets' so far. But there's nothing stopping you from creating your own genesis block (although it's pretty pointless).

I was interested in trying to create on just to understand the process better. – user4381 – 2013-04-15T08:37:27.703

1Do you mind elaborating on these 3 "test nets"? – Pacerier – 2014-05-25T05:52:09.700