<p>A valid block is found when any miner authors a block candidate whose block hash interpreted as a number is lower than the target. This is equivalent to meeting or surpassing the required <a href="https://bitcoin.stackexchange.com/q/5838/5406">difficulty</a>.</p>

<p>To this end, miners create templates of a block that they would like to confirm by selecting a set of transactions and creating their unique <a href="https://bitcoin.stackexchange.com/q/4571/5406">coinbase transaction</a> to collect the <a href="https://bitcoin.stackexchange.com/q/17999/5406">block reward</a>. Each block template can be tried a number of times by cycling through all possible values of the arbitrarily picked <a href="https://bitcoin.stackexchange.com/q/1290/5406">nonce</a> in the <a href="https://bitcoin.stackexchange.com/q/12427/5406">block header</a>. After that, the template can be slightly adapted e.g. by changing the <a href="https://bitcoin.stackexchange.com/q/1482/5406">block time</a> in the header, by incrementing the <a href="https://bitcoin.stackexchange.com/q/5048/5406">extranonce</a> in the coinbase transaction or introducing any other change into the block template.</p>

CC BY-SA 3.0
2017-10-31T09:37:29.810Z
Please note  that I've linked a few related topics for your convenience.
Murch
CC BY-SA 3.0
2017-10-31T16:33:53.187Z
Thank you for the answer! It helped :D I checked all the links too. I really appreciate your effort and kindness!
JeongIn Kim
CC BY-SA 3.0
2017-10-31T09:13:49.180Z
2017-10-31T09:34:18.003Z
2017-10-31T09:34:18.003Z
Murch
<p>Ok, let’s try to give a helping hand: this certain criteria is the nonce, that must be lower than a “certain” value. The nonce is calculated as a hash value with a certain number of 0 at the beginning. It is not the block hash! This nonce value is automatically adopted by the system, there are formulas behind, that try to achieve a block creation every ten minutes. If there is too many miners with too much hash power, the difficulty increases, otherwise it get’s lowered (or stays the same). The explanation in detail can be found in Andreas’ book “Mastering Bitcoin”, or on Bitcoin.org.</p>

<p>--> correction: 
from Andreas' book: "With all the other fields filled," (which is Version, Previous Block Hash, Merkle Root, Timestamp and Difficulty Target) "... the block header is now complete and the process of mining can begin. The goal is now to find a value for the nonce that results in a block header hash that is less than the difficulty target. The mining node will need to test billions or trillions of nonce values before a nonce is found that satisfies the requirement." </p>

CC BY-SA 3.0
2017-10-31T18:56:31.887Z
I correct my wrong answer ...
pebwindkraft
CC BY-SA 3.0
2017-10-31T08:39:29.670Z
2017-10-31T18:59:43.560Z
2017-10-31T18:59:43.560Z
pebwindkraft
<p>I'm looking for information about Bitcoin. And I read this, it's really helpful.</p>

<p>I already asked the question and many of you guys said it's duplicated, and link to the question "What  exactly is the  mining?" or something.</p>

<p>The thing is, I already read it, and I just need some more specific information about criteria.</p>

<p>One of the answer for "What exactly is the mining?" said</p>

<p>"The way Bitcoin makes sure there is only one block chain is by making blocks really hard to produce. So instead of just being able to make blocks at will, miners have to compute a cryptographic hash of the block that meets certain criteria."</p>

<p>In here, the cryptographic hash should meet the certain criteria. And I wonder what it is, and who decided the criteria. I mean, if computers keep mining hash block to get the bitcoin, there should be a certain criteria like it says above.</p>

<p>Hope anyone can answer this question.</p>

<p>Have a nice day.</p>

<block><mining-theory><difficulty>
What is the "certain criteria" to be a valid Bitcoin block?
JeongIn Kim
# What is the "certain criteria" to be a valid Bitcoin block?

(Asked by: username_0 on 2017-10-31)

I'm looking for information about Bitcoin. And I read this, it's really helpful.

I already asked the question and many of you guys said it's duplicated, and link to the question "What exactly is the mining?" or something.

The thing is, I already read it, and I just need some more specific information about criteria.

One of the answer for "What exactly is the mining?" said

"The way Bitcoin makes sure there is only one block chain is by making blocks really hard to produce. So instead of just being able to make blocks at will, miners have to compute a cryptographic hash of the block that meets certain criteria."

In here, the cryptographic hash should meet the certain criteria. And I wonder what it is, and who decided the criteria. I mean, if computers keep mining hash block to get the bitcoin, there should be a certain criteria like it says above.

Hope anyone can answer this question.

Have a nice day.

**Tags:** block, mining-theory, difficulty


---

## 2 answers

### Answer by username_1 on 2017-10-31. Score: 1 | Accepted answer

A valid block is found when any miner authors a block candidate whose block hash interpreted as a number is lower than the target. This is equivalent to meeting or surpassing the required [difficulty](https://bitcoin.stackexchange.com/q/5838/5406).

To this end, miners create templates of a block that they would like to confirm by selecting a set of transactions and creating their unique [coinbase transaction](https://bitcoin.stackexchange.com/q/4571/5406) to collect the [block reward](https://bitcoin.stackexchange.com/q/17999/5406). Each block template can be tried a number of times by cycling through all possible values of the arbitrarily picked [nonce](https://bitcoin.stackexchange.com/q/1290/5406) in the [block header](https://bitcoin.stackexchange.com/q/12427/5406). After that, the template can be slightly adapted e.g. by changing the [block time](https://bitcoin.stackexchange.com/q/1482/5406) in the header, by incrementing the [extranonce](https://bitcoin.stackexchange.com/q/5048/5406) in the coinbase transaction or introducing any other change into the block template.

> **Comments:**
> **username_1**: Please note  that I've linked a few related topics for your convenience.  
> **username_0**: Thank you for the answer! It helped :D I checked all the links too. I really appreciate your effort and kindness!  

---

### Answer by username_2 on 2017-10-31. Score: 0

Ok, let’s try to give a helping hand: this certain criteria is the nonce, that must be lower than a “certain” value. The nonce is calculated as a hash value with a certain number of 0 at the beginning. It is not the block hash! This nonce value is automatically adopted by the system, there are formulas behind, that try to achieve a block creation every ten minutes. If there is too many miners with too much hash power, the difficulty increases, otherwise it get’s lowered (or stays the same). The explanation in detail can be found in Andreas’ book “Mastering Bitcoin”, or on Bitcoin.org.

--> correction:
from Andreas' book: "With all the other fields filled," (which is Version, Previous Block Hash, Merkle Root, Timestamp and Difficulty Target) "... the block header is now complete and the process of mining can begin. The goal is now to find a value for the nonce that results in a block header hash that is less than the difficulty target. The mining node will need to test billions or trillions of nonce values before a nonce is found that satisfies the requirement."

> **Comments:**
> **username_2**: I correct my wrong answer ...  

---

