What Are Bitcoin Blocks And Bitcoin Confirmations ?
What are Bitcoin Blocks and Bitcoin Confirmations ? Last updated on March 18th, 2015 at 10:43 am Lets say I send you 1 Bitcoin. After a few minutes you see that this transaction has received one confirmation. What does this actually mean? The block chain is built out of blocks. Each new block is a set of new unique Bitcoin transactions that were recently made.So when I broadcasted to the network that I want to send you 1 Bitcoin the transaction went into an unconfirmed transactions pool. Miners entered the unconfirmed transactions pool, took this transaction and others like it, verified they were valid (meaning I actually have the 1 Bitcoin to spend), and grouped them into a block.The new block is set at the top of the blockchain and is considered confirmed. Now miners can move on to build the next block on top of that one. Each time a new block is built it means that the older blocks got confirmed again (since they are checked also in the process). The more confirmations you get, the harder it will be for someone to manipulate the system and remove the block containing this transaction from the wall (or blockchain) since its buried under the other blocks that were confirmed. It is recommended to wait for at least 6 confirmations in order to be 99.9% sure that your transaction wont get canceled this takes roughly 1 hour to achieve. If youre dealing with smaller amounts of money youre probably OK with waiting for just 1 confirmation. Reversing a transaction takes planning, time and effort and a lot of computing power. Most people probably wont go through all of that trouble for a small amount of money. Continue reading >>
Why Is My Bitcoin Transaction Pending And Not Confirming?
Also Read: How to rebroadcast a Bitcoin transaction using Blockchain.infos pushtx feature While the fraudulent bitcoin transaction will not confirm, a transaction with a low fee might confirm or be dropped from the networkifa long enough time has passed.However, the transaction must meet theminimum relay fee (MIN_RELAY_TX_FEE) which is currently set to0.0001 BTC. The minimum relay tx fee is the minimum amount that the transaction fee has to be in order for the particular node to relay the transaction. Before a transaction can be confirmed by the miners it needs to be seen by them, as a result tranasctions that never relay will never get confirmed. So lets say that you sent a transaction with a fee smaller than the MIN_RELAY_TX_FEE, you can still get that transaction to get relayed by a node if the node has overridden theMIN_RELAY_TX_FEE value to be less than 0.0001. According toDavid Schwartz from the Bitcoin Stack Exchange , one of the core developers Luke Dash Jr. runs one such node, with IP address 126.96.36.199 . You can check if your transaction was relayed or not by visiting blockchain.info and searching for either the sending or receiving address or the txid. Simply relaying the transaction isnt enough to get it confirmed, the transaction might need to be relayed over and over until a miner will pick it up and confirm it. Conversely, if you need the transaction to be confirmed urgently and the transaction hasnt been relayed you can try signing the transaction again but this time adding a higher fee. Coinb.in offers great tools to help you sign, broadcast, verify, and create new transactions. This issue of transactions not getting confirmed due to low mining fees set by the sender caused a heated debate when Peter Todd proposed a solution called Full RBF . RBF s Continue reading >>
Confirmation - Bitcoin Wiki
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. Note that unconfirmed transactions do not expire . The classic bitcoin client will show a transaction as "n/unconfirmed" until the transaction is 6 blocks deep.Merchants and exchanges who accept bitcoins as payment can and should set their own threshold as to how many blocks are required until funds are considered confirmed.When potential loss due to double spending as nominal, as with very inexpensive or non-fungible items, people may choose not to wait for a transaction to be confirmed, and complete the exchange as soon as it is seen on the network.Most exchanges and other merchants who bear the risk from double spending require 6 or more blocks. There is nothing special about the default, often-cited figure of 6 blocks. It was chosen based on the assumption that an attacker is unlikely to amass more than 10% of the hashrate, and that a negligible risk of less than 0.1% is acceptable.Both these figures are arbitrary, however;6 blocks are overkill for casual attackers, and at the same time powerless against more dedicated attackers with much more than 10% hashrate.  Freshly-mined coins cannot be spent for 100 blocks.It is advisable to wait some additional time for a better chance that the transaction will be propagated by all nodes.Some older bitcoin clients won't show generated coins as confirmed until they are 120 blocks deep. Transactions Continue reading >>
What Is A Confirmation? : Bitcoin
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What To Do If Your Bitcoin Transaction Gets "stuck"
The number of transactions on the Bitcoin network has steadily increased over the years. This means more blocks are filling up. And as not all transactions can be included in the blockchain straight away, backlogs form in miners mempools (a sort of transaction queue.) Miners typically pick the transactions that pay the most fees and include these in their blocks first. Transactions that include lower fees are outbid on the so called fee market, and remain in miners mempools until a new block is found. If the transaction is outbid again, it has to wait until the next block. This can lead to a suboptimal user experience. Transactions with too low a fee can take hours or even days to confirm, and sometimes never confirm at all. But here is what you can do today to keep your own transaction from getting stuck. For the first years of Bitcoins existence, most wallets added fixed fees to outgoing transactions: typically, 0.1 mBTC. Since miners had spare space in their blocks anyways, they normally included these transactions in the first block they mined. (In fact, transactions with lower fees or even no fee at all were often included as well.) With the increased competition for block space, a fixed 0.1 mBTC fee is often insufficient to have a transaction included in the next block; it gets outbid by transactions that include higher fees. While even a low fee transaction will probably confirm eventually, it can take a while. If you want to have your transaction confirmed faster, the obvious solution is to include a higher fee. If your wallet (by default) includes an insufficient fee, you may be able to adjust the fee manually, either as part of the wallet settings, or when you send a transaction. (Or both.) Websites like 21.co monitor the network and suggest how much of a fee Continue reading >>
Transactions - What Are Bitcoin "confirmations"? - Bitcoin Stack Exchange
Probably you should differentiate between "a 50/50 chance that a double spend is possible" and "a 50/50 chance that a double spend occurred" since many people might take the former to mean the latter. eMansipater Sep 8 '11 at 0:34 This answer could be improved be indicating the chance of a double spend is not 50/50. It is based on the % of hashing power the attacker has (assuming it is less than 50%). Thus if the attacker has 10% of hashing power he has a 10% chance of reversing one block. Roughly a 0.1^2 = 1% chance of reversing two blocks, etc. If the attacker has an 51% of hashing power then this doesn't apply as it requires an infinite number of blocks to ensure the transaction can't be reversed and thus alternative means are necessary to protect the block chain. DeathAndTaxes Nov 23 '11 at 16:35 Most of this post succinctly answers the main question, but the 50/50 section is downright false. It would be great if that could be improved. Murch Oct 22 '14 at 11:22 @Murch the 50/50 comment intentionally leaves out hashing rate because it is an unknown variable. You DO NOT KNOW the hashing rate a *possible* attacker *may* be employing when considering confirmations, but I agree that isn't clearly explained so I will clarify the answer. It is not "downright false", just unclear. Joshua Kolden Oct 23 '14 at 10:32 @JoshuaKolden Sorry, "downright false" was indeed the wrong way to put it. What I meant was: Maybe the expression "50/50" is used differently colloquially, but reading "about a 50/50 chance" would to me imply equal chances (50%/50% out of 100%) for each case. To somebody at the knowledge stage of asking "What is a confirmation?" it would sound as if double-spending is frequent, as well as much more likely to succeed than it is in reality, and that one should alw Continue reading >>
Bitcoin Block Explorer - Blockchain
Like paper money and gold before it, bitcoin and ether allow parties to exchange value. Unlike their predecessors, they are digital and decentralized. For the first time in history, people can exchange value without intermediaries which translates to greater control of funds and lower fees. Search You may enter a block height, address, block hash, transaction hash, hash160, or ipv4 address... Continue reading >>
Dirty Politics Responsible For Confirmation Queues On Bitcoin Blockchain
Dirty Politics Responsible for Confirmation Queues on Bitcoin Blockchain There are actors in the system sending thousands of transactions to themselves in order to add leverage to the block size debate. As the number of unconfirmed Bitcoin transactions keeps increasing, a lot of users are left frustrated either by paying very high fees or experiencing protracted delays in their transactions. Most users are seeking ways to facilitate their already delayed transaction. Some patronize online services that claim to accelerate transaction confirmation, while others engage platforms that they believe would offer the opportunity to broadcast such transactions to the miners community. In order to find a solution, the root cause of any given problem must be identified. With a market capitalization of over $32 bln, and a daily trading volume of almost $1 bln it is obvious that there is a significant increase in the adoption of Bitcoin. This is reflected by the cryptocurrency reaching a new all-time high of $1,960 in price. Despite the increased adoption and volume of transaction, the sudden hike in the rate of unconfirmed transaction raises interest from certain quarters. While advising users on ways to effectively achieve transfer of value without frustrations, Blockchain Consultant, Timothy Suggs notes the possible reasons for the increased delays in the transaction. "Bitcoin transaction times are lagging right now for various reasons, one being exponential growth and acceptance of the platform and another being political reasons. By political I mean, there are actors in the system sending thousands of transactions to themselves in order to add leverage to the block size debate. However, Suggs notes that to speed up their transaction time users can increase their fee or engage Continue reading >>
This is the approved revision of this page; it is not the most recent. View the most recent revision. Transaction confirmation is needed to prevent double spending of the same money. Usually when new Bitcoins are earned the owner isn't free to utilize them immediately. As soon as transaction is started it is sent to Bitcoin network for proccessing and has to be included in a block before becoming legitimate. The process of implementing a transaction in a newly found block is called a transaction confirmation. Inclusion in one block = one confirmation and when there are six or more of such confirmations the transaction is considered confirmed. This feature was introduced to protect the system form repeated spending of the same bitcoins (double-spending). Inclusion of transaction in the block happens along with the process of mining . Classic Bitcoin client will show the transaction as "unconfirmed" until there are six confirmations (six found blocks ). Sites or services that accept Bitcoin as payment for their products or services can set their own limits on how many blocks are needed to be found to confirm a transaction. The number six was chosen deliberately: it is based on a theory that there's low probability of wrongdoer being able to amass more than 10% of entire network's hashrate for purposes of transaction falsification and an insignificant risk (lower than 0.1%) is acceptable. For offenders who don't possess significant computing power 6 confirmations are an insurmountable obstacle. In their turn people who possess more than 10% of power aren't going to find it hard to get 6 confirmations in a row. However to obtain such a power would require millions' dollars worth of investments which lowers the risk of an attack. Bitcoins that are distributed by network for Continue reading >>
How Long Does It Take For A Bitcoin Transaction To Be Confirmed?
How long does it take for a Bitcoin transaction to be confirmed? Stanford researcher Dr. Joseph Bonneau explains the distinction between confirmed and unconfirmed Bitcoin transactions. [For the latest on policy and regulation relating to cryptocurrencies like Bitcoin, see what we're doing to protect your right to innovate with cryptocurrencies .) Frequently in popular descriptions of Bitcoin and in the user interfaces of wallet software, a distinction is made between confirmed and unconfirmed transactions. What is the difference? At a high level, a transaction is only confirmed when it is permanently included in the Bitcoin blockchain. The blockchain is a ledger of all transactions in the history of Bitcoin. It is append-only, meaning new data can be added to the end of the ledger, but data can never be removed once included. This ledger is necessary to prevent double-spending, which is a key technical challenge in designing any cryptocurrency. Recall that if Alice owns some quantity of bitcoins, this really means she knows one or more cryptographic keys which have been designated as the controller of those coins in a transaction on the ledger which transferred the coins to Alice. In order to transfer the coins to another entity, Alice will use these keys to produce a digital signature on the statement I would like to redeem (spend) this transaction and send the value to X, Y, Z where X, Y, and Z will be new cryptographic addresses representing keys known by other individuals (or perhaps Alice herself). Now, suppose Alice signs a statement on her own computer saying she wants to transfer some coins to Bob but never sends the statement to Bob. In this case, clearly the coins have not been transferred. This is roughly like a tree falling in the forest with nobody around Continue reading >>
How Do Bitcoin Block Confirmations Work?
When you make a bitcoin transaction, it goes into a pool of unconfirmed transactions. Then, bitcoin miners select your transaction and place it into a block of transactions. The miner solves a special mathematical puzzle called a proof of work. After that, the Bitcoin Network confirms your block and adds it to the blockchain. Each new block added to the blockchain is another confirmation for your transaction. Because you need an enormous amount of computing power to solve these puzzles, they are difficult to undo. This is because each puzzle builds upon the previous blocks so to get to block #2, you would need to also undo blocks #7, #6, #5, #4, and #3. This would take a nearly impossible amount of computing power, so your bitcoin is as secure as possible after six confirmations. Sometimes, your transaction will be unconfirmed for a long period of time. This is likely because you did not include a large enough bitcoin miner fee or were using a bitcoin exchange to pay (exchanges do not attach bitcoin miner fees). Miner fees are like the shipping you pay when ordering something online. They encourage the miner to select your transaction. Bitcoin exchanges often try to send their transactions as efficiently as possible. This can mean that the fee is not large enough or doesnt arrive quickly enough for a miner to include your transaction in the next block. To get around these problems, you should use [a bitcoin wallet](bitpay.com/how-to-secure-bitcoin). We recommend the BitPay Wallet not only because it is ours, but because it can integrate with the largest bitcoin exchange, Coinbase . Continue reading >>
Bitcoin Transaction Delays
For the past few weeks, there have been increased transaction delays on the Bitcoin network, something which affects all Bitcoin providers and users all around the world. When you send Bitcoin, the transaction may be instantly broadcast to the Bitcoin network, but will not immediately be confirmed. Most wallets, like Luno, require three blockchain confirmations before it will show up as completed, some may require up to six. Luno doesnt have full control over the speed that transactions get confirmed on the blockchain, neither does any other single company or entity. Approximately every ten minutes, a new block is created and added to the blockchain through a process called mining . Each block verifies and records any new transactions (such as the Bitcoin you may be sending). These transactions are then confirmed by the Bitcoin network. For example, if Jodi sends two Bitcoins to Werner, this transaction will remain unconfirmed until the next block is created. Once the next block is created and the new transaction is verified and included in that block, the transaction will have one confirmation. Approximately every ten minutes thereafter, a new block is created and the transaction is reconfirmed by the Bitcoin network. As mentioned above, blocks are usually confirmed at approximately one block every ten minutes. However, the Bitcoin network can currently only handle a finite amount of transactions per block. Each transaction has a certain size in bytes and each block can only contain a certain number of bytes. When a lot of transactions are being broadcasted --faster than what the network can currently process it-- it creates a backlog of unconfirmed transactions. Backlogs happen occasionally, but the network eventually resolves all of the transactions within a day or Continue reading >>
How Long Do Bitcoin Transactions Take?
The short answer: How long it takes to transfer Bitcoin between wallets varies from transaction to transaction. When you make a Bitcoin transaction, it needs to be approved by the network before it can be completed. The Bitcoin community has set a standard of 6 confirmations that a transfer needs before you can consider it complete. What determines the Bitcoin transaction times? The two main factors influencing the transaction time are: The more transactions that the network needs to process, the longer each transaction takes. This is because there are only a finite number of miners to process each block and there are a finite number of transactions that can be included in a block. Miners on the Bitcoin network prioritize transactions by the fee that they receive for confirming them. Therefore, if you pay a higher fee , a miner is more likely to process your transfer which decreases the transaction time. How long does it take to confirm a Bitcoin transaction? As mentioned earlier, a Bitcoin transaction generally needs 6 confirmations from miners before its processed. The average time it takes to mine a block is 10 minutes, so you would expect a transaction to take around an hour on average. However, the recent popularity boom of Bitcoin has caused congestion on the network. The average time for one confirmation has recently ranged anywhere from 30 minutes to over 16 hours in extreme cases. Theres been a divide in the Bitcoin community on how to best address these scaling issues. Some members (specifically those in favor of Bitcoin Cash ) believe that the solution is a larger block size thats capable of holding more transactions per block. Other community members debate that improvements such as Segregated Witness (SegWit) and the Lightning Network will speed up the net Continue reading >>
How Do Bitcoin Transactions Work? - Coindesk
Bitcoin transactions are sent from and to electronic bitcoin wallets , and are digitally signed for security. Everyone on the network knows about a transaction, and the history of a transaction can be traced back to the point where the bitcoins were produced. Holding onto bitcoins is great if you’re a speculator waiting for the price to go up, but the whole point of this currency is to spend it, right? So, when spending bitcoins, how do transactions work? There are no bitcoins, only records of bitcoin transactions Here’s the funny thing about bitcoins: they don’t exist anywhere, even on a hard drive. We talk about someone having bitcoins, but when you look at a particular bitcoin address, there are no digital bitcoins held in it, in the same way that you might hold pounds or dollars in a bank account. You cannot point to a physical object, or even a digital file, and say “this is a bitcoin”. Instead, there are only records of transactions between different addresses, with balances that increase and decrease. Every transaction that ever took place is stored in a vast public ledger called the block chain. If you want to work out the balance of any bitcoin address, the information isn’t held at that address; you must reconstruct it by looking at the blockchain. If Alice sends some bitcoins to Bob, that transaction will have three pieces of information: An input. This is a record of which bitcoin address was used to send the bitcoins to Alice in the first place (she received them from her friend, Eve). An amount. This is the amount of bitcoins that Alice is sending to Bob. An output. This is Bob's bitcoin address. To send bitcoins, you need two things: a bitcoin address and a private key. A bitcoin address is generated randomly, and is simply a sequence of lett Continue reading >>
3 Things To Know About Bitcoin Confirmations
Roughly every ten minutes, a new block is created and added to the blockchain through the mining process. This block verifies and records any new transactions. The transactions are then said to have been confirmed by the Bitcoin network. For example, if Sean sends one bitcoin to John, this transaction will remain unconfirmed until the next block is created. Once that block is created and the new transaction is verified and included in that block, the transaction will have one confirmation. Approximately every ten minutes thereafter, a new block is created and the transaction is reconfirmed by the Bitcoin network. While some services are instant or only require one confirmation, many Bitcoin companies will require more as each confirmation greatly decreases the likelihood of a payment being reversed. It is common for six confirmations to be required which takes about an hour. How many Bitcoin Confirmations are Enough? Payments with 0 confirmations can still be reversed! Wait for at least one. One confirmation is enough for small Bitcoin payments less than $1,000. Enough for payments $1,000 - $10,000. Most exchanges require 3 confirmations for deposits. Enough for large payments between $10,000 - $1,000,000. Six is standard for most transactions to be considered secure. Suggested for large payments greater than $1,000,000. Less is likely fine, but this is to be safe! Once you make a transaction, your wallet should give you an option to view the transaction on a block explorer or give you the transaction ID. A transaction ID looks like this: 7a43510802e113b7059851ef0a8a5c3625db37541861dd982f56253b2d5c4ff9 To check the number of confirmations for a transaction, paste the ID into a block explorer like blockchain.info: Press enter and then youll see more details about your t Continue reading >>