Why Should people wait for confirmation of Bitcoin?

[clickerz]

No, a single input has 148 (compressed pub key) or 180 (uncompressed pub key) byte. An input can be worth any (valid) amount of bitcoin. A transaction spends inputs and creates outputs (~34 bytes each).

@shorena Thank you for the explanation I really appreciate it.

we all know that one of the factors that affect the speed of delivery of bitcoin is the amount of the fee we include.
so the larger the fee it will be more easily split the bitcoin block. so that will make financial transactions faster we sent.

No, your fee will not decrease the time miners need to find a valid block. It will only give miners an incentive to put your transaction into the next block. Raising the fee beyond a certain amount is pointless.

This is the common misconception I think most of us here believe. The higher the fee, the faster the transaction. 

[shorena]

-snip-
This is the common misconception I think most of us here believe. The higher the fee, the faster the transaction. 

The next block has room for ~2000-2500 transactions (500-400 byte average), if your fee is high enough to be in the top 2000 its enough. You can pay extra to be top 10, but its still the same block.

[Red Fish]

Yes, in gambling sites - if you invest Bitcoins, play, win and want to withdraw, gambling site will wait for all confirmations before withdraw. It is strange, but most possible gambling sites received some fake BTC transactions, therefore they wait for all confirmations.

[Kprawn]

Bitcoin do not have a central entity that validates all the transactions being done, because it is a decentralized network. So to simplify things,

the network of people help to validate that the bitcoins you are using in your current transaction, was not spend before. The more people

doing this, the stronger the validation. It is things like this, that makes Bitcoin special.  ... Some of the guys here are too technical. 

[RGBKey]

I know most people here have already told you it's because of double spending, but I'd like to elaborate on why you so rarely see double spending attempts now: because people wait for confirmations. If people didn't wait for confirmations, there would likely be many more double spending attempts.

[shield132]

I just thought about this today. Every time you are transacting with bitcoin, you will be told that you have to wait for bitcoin confirmation. This is common with bitcoin gambling sites. What I know is that bitcoin transactions are irreversible. Then why is it that you have to wait for the confirmation before initiating anything?

Situation is different on many webaite. For example bitpay accept bitcoin payments with only one confirmation. Also there are gambling websites which are immediately adding your coins without confirmation but it doesn't mean they you will withdraw them without confirmation. Confirmation is for to be secure against double spending.
You can see more detailed information here: https://en.bitcoin.it/wiki/Confirmation

[Daneric]

I just thought about this today. Every time you are transacting with bitcoin, you will be told that you have to wait for bitcoin confirmation. This is common with bitcoin gambling sites. What I know is that bitcoin transactions are irreversible. Then why is it that you have to wait for the confirmation before initiating anything?

After a transaction is broadcast to the Bitcoin network, it may be included in a block that is published to the network. When that happens it is said that the transaction has been mined at a depth of 1 block. With each subsequent block that is found, the number of blocks deep is increased by one. To be secure against double spending, a transaction should not be considered as confirmed until it is a certain number of blocks deep.

maybe you can get more information from this article. https://en.bitcoin.it/wiki/Confirmation

Thanks for the link. A very good source of information. Indeed the confirmation of transactions is explained in detail.

[calkob]

they are only irreversible after a certain amount of confirmations, i think its about 6

[Mydarksaviour]

yes, i agree with the comments here. if we will not wait for the confirmations then we may have double spending those coins. besides its not too much to ask to just wait 10-25 minutes right.

[franky1]

they are only irreversible after a certain amount of confirmations, i think its about 6

technically its more.. thats why block rewards are unspendable for 100 confirms.

but the chance of a orphan block is 1-2% (atmost risk is 3blocks a day)
in a period where upgrades and consensus changes are happening where pools wont do anything to the blocks unless >95% compliance, means a <5% risk = ~6-7 blocks might orphan

so in a time when there is a bug or a time of consensual feature upgrade where risks are higher, some services may request upto 10-20 confirms, until the risk level subsides.

as for the "trust" / honourability between buyer and seller of zero confirms.. its still not good
some people say its ok to risk $1-2 without confirming.. but.

people buying something for $1-$2 may only see it as value of a loaf of bread in western countries so no big deal.
but people making $1-$2 transaction is not going to pay 7cents-14cents to make such a purchase (7% cost)
so chances are the tx wont even have a fee and it WILL get dropped by the network rather than accepted into a block.

also in the third world. that $1-$2 is a weeks wages. and the tx fee is 1-3 hours minimum wage labour. again chances are no fee added
again dont trust it, if you are transacting with someone from a developing country. treat $2 spend as if they were trying to spend $400 U.S.
you may think its just a loaf of bread. but they think of it as a weeks wage so would be happy to put the effort in to double spend and keep the weeks wage.

its not about how much you spend. its about WHO you are transacting with and the tell tell signs that the transaction may or may not get into a block EG low fee, or opted in for RBF or spot the same inputs being used elsewhere

[Capradina]

yes, i agree with the comments here. if we will not wait for the confirmations then we may have double spending those coins. besides its not too much to ask to just wait 10-25 minutes right.

It also depends on the level of confirmation from the miners, if they have a very fast then the confirmation level we have also quickly. Only now the mining rate is extremely difficult. so I think indeed the level of confirmation right now is very low, it will not be a problem if confirmation still estimate in terms of standards and do not have a low transaction fee rate

[arransiv]

I just thought about this today. Every time you are transacting with bitcoin, you will be told that you have to wait for bitcoin confirmation. This is common with bitcoin gambling sites. What I know is that bitcoin transactions are irreversible. Then why is it that you have to wait for the confirmation before initiating anything?

Maybe because if you use a low fee, you can revert your transaction.

Also if you don't depend of any confirmation, the blockchain will be useless, the "3" confirmations is something to avoid scammers.

[aarons6]

instead of worry about double spend, it's far more likely you will get a tx with too low of fee and it will be rejected before its confirmed.. this has happened to me twice..

[Selly Arumsari]

I just thought about this today. Every time you are transacting with bitcoin, you will be told that you have to wait for bitcoin confirmation. This is common with bitcoin gambling sites. What I know is that bitcoin transactions are irreversible. Then why is it that you have to wait for the confirmation before initiating anything?

in my opinion , wait for confirmation very important because this is ensure really you not other people
and purpose for confirmation is you accept your transaction..

[acroman08]

May I ask franky1, shorena, how some casino are able/willing to accept deposits without confirmations?
How do you think they know for sure that the coins were really sent/no double transact?
Is it really just because they control the withdraw process so they can afford the no confirm for deposits? Or are there any other reasons?
Also, do you know of any way one might be able to calculate the transaction size?

(sorry bout my questions ^^)

[davis196]

I just thought about this today. Every time you are transacting with bitcoin, you will be told that you have to wait for bitcoin confirmation. This is common with bitcoin gambling sites. What I know is that bitcoin transactions are irreversible. Then why is it that you have to wait for the confirmation before initiating anything?

I think that before 3 confirmations the transaction is actually reversible.

During the confirmation time you can refund,if there is something wrong with your purchase.

Some people really hate to wait for confirmations and maybe this stops bitcoin growth and mass adoption.

[Carlsen]

A confirmation means that the transaction is written in a block.
From all I know a block can be mined by two people at the same time, then it takes a little until the network has decided which block it wants to follow.
After a few blocks the network has made that decision.
So it's better to wait that time. Otherwise there is a really small chance that the transaction will be reversed.

[serjent05]

I have not yet made a transaction where there is double spent but it's likely to happen so users should wait for the confirmation before proceeding,sometimes it takes long time to confirm but this is the only drawback but I still prefer to transact using crypto currency than paypal or payza.

there is always some people to play and exploit the system.  And for bitcoin it is the double spend.  The confirmation is the counter of bitcoin system to this kind of bad behaviour.  You maybe don't have an intention to exploit this possible glitch of bitcoin transaction but I am sure there are shady people out there that doesn't care about anything else but to get easy money.

[Juggy777]

I just thought about this today. Every time you are transacting with bitcoin, you will be told that you have to wait for bitcoin confirmation. This is common with bitcoin gambling sites. What I know is that bitcoin transactions are irreversible. Then why is it that you have to wait for the confirmation before initiating anything?

It is done for security reasons and so that you can be protected by yourself and the other user also gets protects himself. If this would not be people would double spend it and it would create caous. It's irritating but it's for our good only. So try and bear with it.

[puremage111]

From what i read previously, it is due to avoid something called double spend, even i am not sure how is it work, but its something like in the olden days where ATM in Location A and Location B is not centralized and sync, so people can withdraw their initial deposit twice.

I think its something like that if i am not mistaken