Questions in the mind of a Beginner.

[Kavelj22]

Edit: Topic moved from beginners board.

Hello

I can consider myself as "smart-enough" to self-learn about bitcoin and how it works, by only reading and make the right step based in different experiences of others.
But there some questions that always came into my mind.
Those questions maybe asked by any other user like me without an academic or technical background.

A- What should happen to unconfirmed transactions? I heard about important amounts stuck in old unconfirmed transactions. Is this real?

B- Is it possible for a miner to:

• Confirm a transaction without fees or with 1 Satoshi per byte?
• Confirm his own transaction?

C- If tomorrow 1 Satoshi becomes equal to 10$, would I say that I can't send 5$ in BTC? Otherwise, is it possible to split those decimals of bitcoin?

D- Is it recommended to wait for more than one confirmation to spend an output? If yes, then why?

E- I remember reading about adding data to a transaction data. Is this possible? If yes, what kind of data can be added? And is this useful for anything?

May be some questions looks dumb but I really face some difficulties to search about them. I want answers in this thread to be a good reference of responses for all of asked questions.

Thank you all who will reply.

[joniboini]

1. They'll be dropped off from the mempool if another transaction pushed them. Most of the times this happens in a few days IIRC. If there are some important transactions that got stuck as an unconfirmed transaction, you can use RBF or child pay for parents to make it confirmed, or wait to get it pushed out from the mempool and make a new transaction.

2. 1 sat is possible, you can't set fees lower than 1 sat atm. He can mine his own transaction.

3. Yes, you can send a fraction of Bitcoin. If 0.0001 BTC equals to $10, you can send 0.00005 BTC.

4. Yes, because more confirmation means that the chance to double spend the transaction is lower.

5. Yes, data such as text, or script iirc. It's useful for a lot of things. Timestamping, anchoring a document/certificate hash, for fun, and so on. Remember, computer data is just a combination of zero and one.

[khaled0111]

A- each node has a maxmempool size (300mb by default) and mempoolexpiry time (336 hours/14 days by default). A bitcoin node has to drop low-fee transactions at some point to be able to accept new ones with higher fees.
Usually, it takes less than 14 days for an unconfirmed transaction to be dropped from all nodes and then you will be able to spend its inputs.

B- . a regular user can't, because zero fee transactions won't be relayed. However, a miner can include the transaction in his block.
    . yes.

C- I think sending a fraction of Satoshi will require a global consensus.

D- each new block equals one more confirmations. The more confirmations there are, the less chances of success for a double-spending attack.
It is recommanded especially for merchants and exchanges. 6 confirmations is safe enough.

E- the best way to do that is by using OP_RETURN. I don't think it is useful, it is spam except for the message left by Satoshi in the genesis block.

[bob123]

Some questions have been answered correctly, so i'll focus on those 3 which i don't like the answers to:

B- Is it possible for a miner to:

• Confirm a transaction without fees or with 1 Satoshi per byte?
• Confirm his own transaction?

A miner can (when he mines a block) include any transaction he wants to (as long as it is a valid transaction; so no double-spends or anything else which would be rejected by the network).
Therefore he can include 0-fee transaction, and he also can include his own transactions (as long as they are valid and accepted by the network!)

If a miner decides to include a non-valid transaction (which he theoretically can), the block will be rejected by the network resulting in the miner having wasted his energy and losing his mining reward.

C- If tomorrow 1 Satoshi becomes equal to 10$, would I say that I can't send 5$ in BTC? Otherwise, is it possible to split those decimals of bitcoin?

Yes, 1 satoshi can be split into even smaller fractions.
This would require a soft fork. Afterwards you would be able to spend 1/10.000.000 of a satoshi (for example).

D- Is it recommended to wait for more than one confirmation to spend an output? If yes, then why?

You can spend your UTXO whenever you wish (with 1 confirmation at least).
But the 'finalness' of this specific UTXO (and therefore of all newly generated from this one) depends on the 'amount of confirmations'.

You can spend funds a UTXO with 1 confirmation, however when dealing with big sums (i am not talking about ~1000$ here), you should wait for more confirmations to be on the safe site.

[Kavelj22]

Thank you so much for your explanation; you made it more clear for me about those questions. I wish I can also know from you about adding data to the Blockchain; how to add those data and in which format and for how long? Should I pay additional fees for this? Here we are talking about the Blockchain for bitcoin, what about others like Ethereum or Dash? I remember hear about some projects that allow storing data within a dedicated blockchain "filecoin" and as usual I didn't succeed to understand the concept.

[HCP]

I wish I can also know from you about adding data to the Blockchain; how to add those data and in which format and for how long? Should I pay additional fees for this?

You use the OP_RETURN opcode... it allows for adding up to 80 bytes worth of data into an (unspendable) output. Services like OMNI use it.

More details on the specifics of OP_RETURN here: https://en.bitcoin.it/wiki/Script#Flow_control
And a pretty indepth explanation of how it is used (although it is missing the revert to 80 bytes that happened late 2015) is here: https://bitcoin.stackexchange.com/q/29554
And a list of recent OP_RETURN transactions is here: http://coinsecrets.org/

As for fees... well you don't necessarily need to pay any additional fee to use OP_RETURN, but as bitcoin transaction fees are essentially based on the overall data size of your transaction, if you are adding an extra 80 bytes of data, the total fee paid will increase.

[bitmover]

C- If tomorrow 1 Satoshi becomes equal to 10$, would I say that I can't send 5$ in BTC? Otherwise, is it possible to split those decimals of bitcoin?

Yes, 1 satoshi can be split into even smaller fractions.
This would require a soft fork. Afterwards you would be able to spend 1/10.000.000 of a satoshi (for example).

As far as I know, lightning network is already allowing payments and fees of less than one satoshi. I know those transactions are off-chain, but it´s an interesting perspective to split satoshi even without forks.

[bob123]

As far as I know, lightning network is already allowing payments and fees of less than one satoshi. I know those transactions are off-chain, but it´s an interesting perspective to split satoshi even without forks.

Yes that's indeed true.

But since the smallest on-chain unit currently is 1 satoshi, upon closing the channel the balance is going to be rounded down to the nearest satoshi.
1.5 satoshi for example would result in getting 1 satoshi when the channel is being closed.

To fully have units smaller than a satoshi, a soft fork is still necessary.

[Thirdspace]

B- Is it possible for a miner to:

• Confirm a transaction without fees or with 1 Satoshi per byte?
• Confirm his own transaction?

yes, it is possible
a miner can include any valid transactions with no fee into a block that miner found
but a 0-fee transaction will not be relayed/broadcasted by any nodes

D- Is it recommended to wait for more than one confirmation to spend an output? If yes, then why?

it doesn't matter, as long as the utxo remains valid in tx mempool your transaction can be relayed
however to get your transaction confirmed, the previous transaction must be confirmed first
so at best case, both transactions will get first confirmation in the same block

on the other hand, when completing a trade deal you need to wait at least 1 confirmation
don't send anything back to the sender of that payment before you see it confirmed on the blockchain

[ranochigo]

A miner can include is/her own transaction with 0 fee as long it is valid. Seding a fraction of satoshi is possible but will require a consensus.

It will require a hard fork as it won't be backward compatible.

This will also majorly depends on the price of BTC at that time. it is good to wait for 1 transaction to be confirmed before spending, if a transaction is rejected from mempool, it will be unspendable, so it is necessary to wait and confirm that the transaction is legit.

Transactions are only rejected from mempool if they are invalid. Due to the limited space of the mempool, nodes usually exclude transactions after a relatively long period of time. In the case that it happens, the transaction won't become invalid; simply rebroadcast the raw transaction and it would be back in the mempool.

[Lily_Olive]

Awww thanks alot for this explanation.. i have read meny articles but i can't  understsnd.. but your post is very effective to understand.. again thanx.. may i know bitcoin  has  any expiry  date?

[bob123]

What do you mean with 'expiry date' ?

Bitcoin itself (the network / protocol) obviously can't expiry.
The UTXOs (funds stored 'on an address') can't expiry too.

Broadcasted (and unconfirmed) transactions can be dropped form the mempool (not really expired).
The consensus is that they will drop out of the mempool after 2 weeks. But single nodes can still keep it longer and broadcast it to prevent a transaction from completely dropping out.
Those transactions still remain valid, even if dropped from the mempool, as long as the inputs are still available.


You need to be a bit more precise. What exactly do you think can or can not expiry ?