<p>The data that's hashed is the <em>block header</em>. You can find a description of the format and layout at <a href="https://en.bitcoin.it/wiki/Block_hashing_algorithm" rel="nofollow">https://en.bitcoin.it/wiki/Block_hashing_algorithm</a></p>

CC BY-SA 3.0
2015-09-29T18:44:22.680Z
How does a Generation block differ? What goes in the `hashPrevBlock` section of the generation block? All zeros?
Corey Ogburn
CC BY-SA 3.0
2015-09-29T18:48:02.233Z
@CoreyOgburn: Do you mean the [genesis block](https://en.bitcoin.it/wiki/Genesis_block), the very first block in the block chain?  Yes, the `hashPrevBlock` field is set to zero.  Everything else is the same.
Nate Eldredge
CC BY-SA 3.0
2015-09-29T16:47:47.140Z
2015-09-29T16:47:47.140Z
Nate Eldredge
<p>I understand that a miner has a list of bitcoin transactions since the last time a a block was discovered. The first entry is the reward for who discovered the previous block. As more transactions gets added, they're appended to this list. This part is speculation, but I think there's also a nonce that the miners inject in order to produce a hash output that meets the difficulty.</p>

<p>Where can I find out the specifics about what exactly is hashed? I'm looking to understand the exact bytes and structure. </p>

CC BY-SA 3.0
2015-11-07T11:54:57.640Z
possible duplicate of [What are bitcoin miners really solving?](http://bitcoin.stackexchange.com/q/8031/5406)
Murch
CC BY-SA 3.0
2015-11-07T11:57:09.010Z
The first entry is _not_ the reward for who discovered the previous block. The first transaction is unique to each miner and causes the block reward of the *upcoming* block to be spend to the miner that discovers the block.
Murch
<blockchain><mining-technical-details>
Where can I find the structure and layout of what exactly gets hashed by miners?
Corey Ogburn
# Where can I find the structure and layout of what exactly gets hashed by miners?

(Asked by: username_0 on 2015-09-29)

I understand that a miner has a list of bitcoin transactions since the last time a a block was discovered. The first entry is the reward for who discovered the previous block. As more transactions gets added, they're appended to this list. This part is speculation, but I think there's also a nonce that the miners inject in order to produce a hash output that meets the difficulty.

Where can I find out the specifics about what exactly is hashed? I'm looking to understand the exact bytes and structure.

**Tags:** blockchain, mining-technical-details

> **Comments:**
> **username_1**: possible duplicate of [What are bitcoin miners really solving?](http://bitcoin.stackexchange.com/q/8031/5406)  
> **username_1**: The first entry is _not_ the reward for who discovered the previous block. The first transaction is unique to each miner and causes the block reward of the *upcoming* block to be spend to the miner that discovers the block.  

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## 1 answers

### Answer by username_2 on 2015-09-29. Score: 2 | Accepted answer

The data that's hashed is the *block header*. You can find a description of the format and layout at <https://en.bitcoin.it/wiki/Block_hashing_algorithm>

> **Comments:**
> **username_0**: How does a Generation block differ? What goes in the `hashPrevBlock` section of the generation block? All zeros?  
> **username_2**: @CoreyOgburn: Do you mean the [genesis block](https://en.bitcoin.it/wiki/Genesis_block), the very first block in the block chain?  Yes, the `hashPrevBlock` field is set to zero.  Everything else is the same.  

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