<p>A new block is <em>ready</em> to hash as soon as the last block has been solved. Miners immediately start to try solving the next block. As soon as one of them succeeds, that block is published and all the miners move to work on the following one.</p>

<p>The <em>difficulty</em> is adjusted so that a solution is found by somebody, out of all the active miners, on average about once every 10 minutes.</p>

CC BY-SA 3.0
2016-04-28T00:46:54.510Z
How does it happen that there was a situation that 3 blocks was relayed in 3 minutes? That's impossible that more than 50% of miners had so huge hashing power to solve the block in 1 minute...
Sebastian Xawery Wiśniowiecki
CC BY-SA 3.0
2016-04-28T00:48:11.463Z
@XaweryWiśniowiecki: The time to solve each block is determined only by chance. In the case you described, different miners got lucky and found a solution quickly three times in a row. This has nothing to do with 51%.
Greg Hewgill
CC BY-SA 3.0
2016-04-28T00:49:34.413Z
Block is added to blockchain if more than 50% of miners say that it is solved correctly. And to do it they also have to solve it and compare results...
Sebastian Xawery Wiśniowiecki
CC BY-SA 3.0
2016-04-28T00:54:44.077Z
@XaweryWiśniowiecki: All the other miners don't have to *solve* the block again, because they already have a solution. They only have to *verify* that the solution is correct, which is a simple calculation.
Greg Hewgill
CC BY-SA 3.0
2016-04-28T01:00:15.440Z
Thanks. Do you know any article about solving and verifing calculations? I was mistaken by some article I have read :/
Sebastian Xawery Wiśniowiecki
CC BY-SA 3.0
2016-04-28T01:04:29.680Z
@XaweryWiśniowiecki: I'm not sure where there might be an article on this. Many people have written about bitcoin, so there's one out there somewhere. But here's a similar question with another explanation: https://bitcoin.stackexchange.com/questions/10849/solving-a-block-and-verification-of-transactions
Greg Hewgill
CC BY-SA 3.0
2016-04-28T00:25:26.477Z
2016-04-28T00:25:26.477Z
Greg Hewgill
<p>Each miner starts working on a new block, as soon as they hear about the latest one being found. </p>

<p>To that end, miners create block candidates and apply the hashing function. As the outputs are determininistic, yet unpredictable, this is effectively a random process where each attempt has a minuscule chance of surpassing the target difficulty. </p>

<p>Whenever one miner manages to find a block candidate that is below the target, they have successfully found a new block. This could happen seconds after the previous block was found, or much later. The difficulty is kept at a level such that <a href="https://bitcoin.stackexchange.com/q/855/5406"><em>in average</em> it is expected to take 10 minutes</a>.</p>

<p>After a block is found, the miner sends it to his peers which redistribute it. Every recipient can simply check that it fulfills the criteria, and then will start working on a successor.</p>

CC BY-SA 3.0
2016-04-28T15:19:47.390Z
2016-04-28T15:19:47.390Z
2017-04-13T12:47:33.610Z
Murch
<p>In addition to the other explanations, it's important to understand that verification of a block takes significant amount of time, and it's consequences. </p>

<p>After a new block is found by a miner, this block is propagated to the rest of the network, including other miners. When other miners receive this news, they have to make a decision. </p>

<p>Should they wait to verify the block first before starting on the next block or start immediately on the next block, and assume that the previous block was legit. The benefit of making the assumption is that there won't be any wasted time spent mining blocks that will stale (orphan), which increases their profit significantly (on the order of ~10%).</p>

<p>As a result, many large mining pools skip this verification process and immediately starts work on the next block. </p>

CC BY-SA 3.0
2016-04-28T23:24:29.507Z
2016-04-28T23:24:29.507Z
mrkent
<p>I know that new blocks are relayed one block per 10 minutes but that time is not exact but average so: Who decides that the new block is ready to hash?</p>

CC BY-SA 3.0
2016-04-28T09:42:11.223Z
Note: There is no "one" block before the hashing starts. Every miner creates their own block and starts hashing on it. They're all different unique blocks by definition. Blocks often change while the hashing is already underway, for example when new transactions are received.
Jannes
<blockchain><mining-theory><difficulty><block-interval>
Who decides that the new block is ready to hash?
Sebastian Xawery Wiśniowiecki
# Who decides that the new block is ready to hash?

(Asked by: username_0 on 2016-04-28)

I know that new blocks are relayed one block per 10 minutes but that time is not exact but average so: Who decides that the new block is ready to hash?

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

> **Comments:**
> **username_1**: Note: There is no "one" block before the hashing starts. Every miner creates their own block and starts hashing on it. They're all different unique blocks by definition. Blocks often change while the hashing is already underway, for example when new transactions are received.  

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## 3 answers

### Answer by username_2 on 2016-04-28. Score: 2 | Accepted answer

A new block is *ready* to hash as soon as the last block has been solved. Miners immediately start to try solving the next block. As soon as one of them succeeds, that block is published and all the miners move to work on the following one.

The *difficulty* is adjusted so that a solution is found by somebody, out of all the active miners, on average about once every 10 minutes.

> **Comments:**
> **username_0**: How does it happen that there was a situation that 3 blocks was relayed in 3 minutes? That's impossible that more than 50% of miners had so huge hashing power to solve the block in 1 minute...  
> **username_2**: @XaweryWiśniowiecki: The time to solve each block is determined only by chance. In the case you described, different miners got lucky and found a solution quickly three times in a row. This has nothing to do with 51%.  
> **username_0**: Block is added to blockchain if more than 50% of miners say that it is solved correctly. And to do it they also have to solve it and compare results...  
> **username_2**: @XaweryWiśniowiecki: All the other miners don't have to *solve* the block again, because they already have a solution. They only have to *verify* that the solution is correct, which is a simple calculation.  
> **username_0**: Thanks. Do you know any article about solving and verifing calculations? I was mistaken by some article I have read :/  
> **username_2**: @XaweryWiśniowiecki: I'm not sure where there might be an article on this. Many people have written about bitcoin, so there's one out there somewhere. But here's a similar question with another explanation: https://bitcoin.stackexchange.com/questions/10849/solving-a-block-and-verification-of-transactions  

---

### Answer by username_3 on 2016-04-28. Score: 2

Each miner starts working on a new block, as soon as they hear about the latest one being found.

To that end, miners create block candidates and apply the hashing function. As the outputs are determininistic, yet unpredictable, this is effectively a random process where each attempt has a minuscule chance of surpassing the target difficulty.

Whenever one miner manages to find a block candidate that is below the target, they have successfully found a new block. This could happen seconds after the previous block was found, or much later. The difficulty is kept at a level such that [*in average* it is expected to take 10 minutes](https://bitcoin.stackexchange.com/q/855/5406).

After a block is found, the miner sends it to his peers which redistribute it. Every recipient can simply check that it fulfills the criteria, and then will start working on a successor.


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### Answer by username_4 on 2016-04-28. Score: 1

In addition to the other explanations, it's important to understand that verification of a block takes significant amount of time, and it's consequences.

After a new block is found by a miner, this block is propagated to the rest of the network, including other miners. When other miners receive this news, they have to make a decision.

Should they wait to verify the block first before starting on the next block or start immediately on the next block, and assume that the previous block was legit. The benefit of making the assumption is that there won't be any wasted time spent mining blocks that will stale (orphan), which increases their profit significantly (on the order of ~10%).

As a result, many large mining pools skip this verification process and immediately starts work on the next block.


---

