Question about bitcoin core fee

[BlackHatCoiner]

In bitcoin core the default transaction fee is 0.0002 BTC/kB

I see that I can change that number. What stops me from doing it 0.00000001? Does it affect my transaction? Beginner here.

[Yourhomeboy]

Yes it will affect your transaction, by delaying the confirmation process. It also make the receiver to refund your money, Because you didn't pay plus fee complete. If it's a cooperate body. I mean. I remember when I made such a mistake, I lost on the long run, Because when I got refunded. My money was not complete.

[odolvlobo]

In bitcoin core the default transaction fee is 0.0002 BTC/kB

I see that I can change that number. What stops me from doing it 0.00000001? Does it affect my transaction? Beginner here.

Miners try to make as much money as they can, so they choose which transactions to include in blocks based on the fees. If you pay more than others, they will choose your transaction before those others. If you pay less, they will choose other transactions first, and it might be a while before they get around to yours.

[MrcMrc]

In bitcoin core the default transaction fee is 0.0002 BTC/kB

I see that I can change that number. What stops me from doing it 0.00000001? Does it affect my transaction? Beginner here.

You transaction will be trapped in the mempool. All transactions will first queue in the mempool where miners will first pick out the the ones with high fee. So, the higher the fee the faster the clearance or transactions time, so, the fee recommended is good for faster transactions. But, if you do not want the bitcoin in short time, you can reduce the fee but reducing it to 0.00000001 btc is too far low, the btc sent will be trapped in the mempool in which no miner will clear your transaction.

[Heisenberg_Hunter]

Fees are certainly based on the transaction volume and the miners trying to pick your transactions to get included in the block. When there is lower transaction volume as like in 2018, you could end up with lower default fees and your transaction will pass sooner even if you have specified a 1 sat/byte fee. Basically a block can have upto 4 million weight units worth of transactions. At the time of writing, blocks are full and the recent #626438 has 3,993,278 weight units. If you are willing to include your transaction in next block to be mined you should be paying the recommended fees which sits at 20-30sat/byte currently.

When there is lesser transactions in the mempool, the miners wouldn't have a go other than picking up your lower fee transaction. If your transaction stays in the mempool for quite a long time i.e either days or a week, it would eventually get removed by the nodes from their unconfirmed transactions. The coins you have sent will be seen as unconfirmed and they can never be spent either unless the transaction gets removed from the pool. This is why Core sets default tx fee for you to prevent such bizarre circumstances.

[BlackHatCoiner]

Fees are certainly based on the transaction volume and the miners trying to pick your transactions to get included in the block. When there is lower transaction volume as like in 2018, you could end up with lower default fees and your transaction will pass sooner even if you have specified a 1 sat/byte fee. Basically a block can have upto 4 million weight units worth of transactions. At the time of writing, blocks are full and the recent #626438 has 3,993,278 weight units. If you are willing to include your transaction in next block to be mined you should be paying the recommended fees which sits at 20-30sat/byte currently.

When there is lesser transactions in the mempool, the miners wouldn't have a go other than picking up your lower fee transaction. If your transaction stays in the mempool for quite a long time i.e either days or a week, it would eventually get removed by the nodes from their unconfirmed transactions. The coins you have sent will be seen as unconfirmed and they can never be spent either unless the transaction gets removed from the pool. This is why Core sets default tx fee for you to prevent such bizarre circumstances.

Okay thanks for the link. The last block's hash right now is: 00000000000000000012b4d3986756787ee41599db2f83269dad8dc98d94df17
So the guess I'm trying to do is the string before that hash get hashed? Look how I'm thinking of it.

We have string.
And we have hash.

SHA256(string) = 00000000000000000012b4d3986756787ee41599db2f83269dad8dc98d94df17

Am I trying to get the string? Is this called mining?


2nd question. If I mine a block (like the last one that exists right now for example), do I get all the fees of all people that made a transaction?


3rd question. Here's an image: https://i.imgur.com/nX5K4Cs.png

It says: "Miner: " and then it has a name of a company (Poolin)? What? We're talking about cryptography here, how do they know who mined it? Isn't bitcoin anonymous?

Thanks to anyone who will solve my questions.

[pooya87]

SHA256(string) = 00000000000000000012b4d3986756787ee41599db2f83269dad8dc98d94df17
Am I trying to get the string? Is this called mining?

not exactly. what you call "string" is something called a block header. it is fixed size and consists of certain parts, some of which are fixed and some can change. for example it has a reference to its ancestor (previous block header hash) and a variable 32-bit integer called nonce that can be changed.
you keep changing the variables and compute the hash (SHA256 of SHA256) until you find a hash that when converted to a 256-bit integer is smaller than the current network's difficulty target.
when you found the correct header you can publish it as a found block.

2nd question. If I mine a block (like the last one that exists right now for example), do I get all the fees of all people that made a transaction?

yes, every block must have a first transaction called coinbase that will pay you two things: 1) the block subsidy (currently it is 12.5BTC) and 2) the total transaction fees. the miner has to create this transaction and set its value correctly before starts mining (build merkle root hash and put it in header).

3rd question. Here's an image: https://i.imgur.com/nX5K4Cs.png

It says: "Miner: " and then it has a name of a company (Poolin)? What? We're talking about cryptography here, how do they know who mined it? Isn't bitcoin anonymous?

there are 2 methods that we can guess who mined a certain block.
1) (most common) to look at the coinbase transaction's signature script and decode it as a string (text) and see if it has the name of the pool. most pools include their own name in it like Poolin then we can assume it is mined by that pool.
2) looking at the outputs of coinbase transaction (the receiving addresses). sometimes pools have known addresses which they use to pay their miners.

note that i say "guess" because we can never be certain the name is real. for instance i can solo mine a block (although it is not possible with the current difficulty within reasonable time, but lets assume it is) and put any name inside that like Poolin. you have no way of knowing whether it was a lie or not.

read more:
https://www.coindesk.com/learn/bitcoin-101/how-bitcoin-mining-works
https://en.bitcoin.it/wiki/Difficulty
https://en.bitcoin.it/wiki/Target
https://en.bitcoin.it/wiki/Proof_of_work

[BlackHatCoiner]

note that i say "guess" because we can never be certain the name is real. for instance i can solo mine a block (although it is not possible with the current difficulty, but lets assume it is) and put any name inside that like Poolin. you have no way of knowing whether it was a lie or not.

So what's the point of knowing the miner? Why do blockchains sites like blockchair or blockchain.info provide that information?

yes, every block must have a first transaction called coinbase that will pay you two things: 1) the block subsidy (currently it is 12.5BTC) and 2) the total transaction fees. the miner has to create this transaction and set its value correctly before starts mining (build merkle root hash and put it in header).

Earlier you said that it's almost impossible to mine the block subsidy only one person. Why is that? I mean if he has a mining farm. Could he be lucky right? I mean 12.5BTC for only one person is about 75.000$. Quite amazing number just from mining.

[naomi-the-cat]

If you will set to low fee you will wait for confromation for a very long time. It may requery week or even more. I can recommend to use fee calculator for this. https://www.buybitcoinworldwide.com/fee-calculator/
0.40 usd is optimal amount right now

[BlackHatCoiner]

If you will set to low fee you will wait for confromation for a very long time. It may requery week or even more. I can recommend to use fee calculator for this. https://www.buybitcoinworldwide.com/fee-calculator/
0.40 usd is optimal amount right now

So the miner just gets 0.40$ from brute forcing my transaction's hash? (and of course, find the correct solution)

BTW I've created a thread with all my cryptocurrency questions: https://bitcointalk.org/index.php?topic=5241534.0

[pooya87]

So what's the point of knowing the miner? Why do blockchains sites like blockchair or blockchain.info provide that information?

well, that's what block explorers do. they provide all kinds of information about the blockchains. also doing that provides a good information (that could be close to reality) about how much hashrate each mining pool has.

Earlier you said that it's almost impossible to mine the block subsidy only one person. Why is that? I mean if he has a mining farm. Could he be lucky right? I mean 12.5BTC for only one person is about 75.000$. Quite amazing number just from mining.

mining farm can not be categorized as a "solo miner", a solo miner is an individual that has little hashrate like having 1 or 2 ASICs. a mining farm has high enough hashrate to be able to have a high enough chance of finding a block on its own.
but a solo miner has to "share the work" so that even when they don't find any blocks, they can still be paid for the work they have done. and with the current difficulty a solo miner has to get super lucky to find a block since the number of hashes that are computed on average is too huge for a solo miner to be able to search on its own.

[BlackHatCoiner]

mining farm can not be categorized as a "solo miner", a solo miner is an individual that has little hashrate like having 1 or 2 ASICs. a mining farm has high enough hashrate to be able to have a high enough chance of finding a block on its own.
but a solo miner has to "share the work" so that even when they don't find any blocks, they can still be paid for the work they have done. and with the current difficulty a solo miner has to get super lucky to find a block since the number of hashes that are computed on average is too huge for a solo miner to be able to search on its own.

So someone that controls a mining farm can open a block everyday on average right? It's 75000$ per day. Does he pay for electricity more than that?

Further, you're saying a solo miner has to share his work. How does this work? I mean, if he open a block can't he just keep it? What stops him from doing it? Does he know that he opened a block?