user8721: I've been doing a lot of reading on mining and software related to mining but I can't quite get my head wrapped around the specific nature of what is being hashed together. So far I feel like the current block header, and a nonce are hashed together in hopes of finding a hash that is less than the current target, if it is, you get 25BTC. Here's where I am confused, according to the psuedocode https://bitcoin.stackexchange.com/a/3047 . The only value that changes is the nonce, and that is a fixed possible hex/integer ex: from 0 to 0xFFFFFFFF.
How is it that the difficulty can increase if there are a finite number of attempts to change the nonce?
Am I right about hashing together the block header with the nonce?
I referenced this https://en.bitcoin.it/wiki/Proof_of_work and it makes perfect sense.. except for the fact that I still feel like the nonce is the only value that changes.
Maybe the 32-bit nonce yields way more possibilities that I can fathom and hashing together every possible nonce value is actually what is done.
Thanks!

user575: When the nonce range is exhausted, miners change the extraNonce field of the generation transaction. This changes the Merkle root in the header and allows a new range of nonces to be attempted.
Since the Merkle root is 256 bits, this can be repeated indefinitely.

8721: <p>I've been doing a lot of reading on mining and software related to mining but I can't quite get my head wrapped around the specific nature of what is being hashed together. So far I feel like the current block header, and a nonce are hashed together in hopes of finding a hash that is less than the current target, if it is, you get 25BTC. Here's where I am confused, according to the psuedocode <a href="https://bitcoin.stackexchange.com/a/3047">https://bitcoin.stackexchange.com/a/3047</a> . The only value that changes is the nonce, and that is a fixed possible hex/integer ex: from 0 to 0xFFFFFFFF.</p>

<p>How is it that the difficulty can increase if there are a finite number of attempts to change the nonce?</p>

<p>Am I right about hashing together the block header with the nonce?</p>

<p>I referenced this <a href="https://en.bitcoin.it/wiki/Proof_of_work" rel="nofollow noreferrer">https://en.bitcoin.it/wiki/Proof_of_work</a> and it makes perfect sense.. except for the fact that I still feel like the nonce is the only value that changes.</p>

<p>Maybe the 32-bit nonce yields way more possibilities that I can fathom and hashing together every possible nonce value is actually what is done.</p>

<p>Thanks!</p>
 575: <p>When the nonce range is exhausted, miners change the extraNonce field of the generation transaction. This changes the Merkle root in the header and allows a new range of nonces to be attempted.</p>

<p>Since the Merkle root is 256 bits, this can be repeated indefinitely.</p>
