147 million bitcoin wiki

Bitcoin was invented by an unknown person or group of people under the name Satoshi Nakamoto [11] and released as open-source software in Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies, [13] products, and services. As of 147 million bitcoin wikiovermerchants and vendors accepted bitcoin as payment. The word bitcoin first occurred and was defined in the white paper [5] that was published on 31 October There is no uniform convention for bitcoin capitalization.

Some sources use Bitcoincapitalized, to refer to the technology and network and bitcoinlowercase, to refer to the unit of account. The unit of account of the bitcoin system is a bitcoin. Named in homage to bitcoin's creator, a satoshi is the smallest amount within bitcoin representing 0.

As with most new symbols, font support is very limited. Typefaces supporting it include Horta. On 18 Augustthe domain name "bitcoin. In Januarythe bitcoin network came into existence after Satoshi Nakamoto mined the first ever block on the chain, known as the genesis block. This note has been interpreted as both a timestamp of the genesis date and a derisive comment on the instability caused by fractional-reserve banking.

The receiver of the first bitcoin transaction was cypherpunk Hal Finneywho created the first reusable proof-of-work system RPOW in In the early days, Nakamoto is estimated to have 147 million bitcoin wiki 1 million bitcoins. So, if I get hit by a bus, it would be clear that the project would go on.

Over the history of Bitcoin there have been several spins offs and deliberate hard forks that have lived on as separate blockchains. These have come to be known as "altcoins", short for alternative coins, since Bitcoin was the first blockchain and these are derivative of it. These spin offs occur so that new ideas can be tested, when the scope of that idea is outside that of Bitcoin, or when the community is split about merging such changes. Since then there have been numerous forks of Bitcoin.

See list of bitcoin forks. The blockchain is a public ledger that records bitcoin transactions. A novel solution accomplishes this without any trusted central 147 million bitcoin wiki The blockchain is a distributed database — to achieve independent verification of the chain of ownership of any and every bitcoin amount, each network node stores its own copy of the blockchain.

This allows bitcoin software to determine when a particular bitcoin amount has been spent, which is necessary in order to prevent double-spending in an environment without central oversight.

Whereas a conventional ledger records the transfers of actual bills or promissory notes that exist apart from it, the blockchain is the only 147 million bitcoin wiki that bitcoins can be said to exist in the form of unspent outputs of transactions. Transactions are defined using a Forth -like scripting language. When a user sends bitcoins, the user designates each address and the amount of bitcoin being sent to that address in an output.

To prevent double spending, each input must refer to a previous unspent output in the blockchain. Since transactions can have multiple outputs, users can send bitcoins to multiple recipients in one transaction. As in a cash transaction, the sum of inputs coins used to pay can exceed 147 million bitcoin wiki intended sum of payments. In such a case, an additional output is used, returning the change back to the payer. Paying a transaction fee is optional. Because the size of mined blocks is capped by the network, miners choose transactions based on the fee paid relative to their storage size, not the absolute amount of money paid as a 147 million bitcoin wiki.

The size of transactions is dependent on the number of inputs used to create the transaction, and the number of outputs. In the blockchain, bitcoins are registered to bitcoin addresses.

Creating a bitcoin address is nothing more than picking a random valid private key and computing the corresponding bitcoin address. This computation can be done in a 147 million bitcoin wiki second. But the reverse computing the private key of a given bitcoin address is mathematically unfeasible and so users can tell others and make public a bitcoin address without compromising its corresponding private key.

Moreover, the number of valid private keys is so vast that it is extremely unlikely someone will compute a key-pair that is already in use and has funds.

The vast number of valid private keys makes it unfeasible that brute force could be used for that. To be able to spend the bitcoins, the owner must know the corresponding private key and digitally sign the transaction. The network verifies the signature using the public key. If the private key is lost, the bitcoin network will not recognize any other evidence of ownership; [9] the coins are then unusable, and effectively lost.

Mining is a record-keeping service done through the use of computer processing power. To be accepted by the rest of the network, 147 million bitcoin wiki new block must contain a so-called proof-of-work PoW. Every 2, blocks approximately 14 days at roughly 10 min per blockthe difficulty target is adjusted based on the network's recent performance, with the aim of keeping the average time between new blocks at ten minutes.

In this way the system automatically adapts to the total amount of mining power on the network. The proof-of-work system, alongside the chaining of blocks, makes modifications of the blockchain extremely hard, as an attacker must modify all subsequent blocks in order for the modifications of one block to be accepted.

Computing power is often bundled together or "pooled" to reduce variance in miner income. Individual mining rigs often have to wait for long periods to confirm a block of transactions and receive payment. In a pool, all participating miners get paid every time a participating server solves a block. This payment depends on the amount of work an individual miner contributed to help find that block.

The successful miner finding the new block is rewarded with newly created bitcoins and transaction fees. To claim the reward, a special transaction called a coinbase is included with the processed payments.

The bitcoin protocol specifies 147 million bitcoin wiki the reward for adding a block will be halved everyblocks approximately every four years. Eventually, the reward will decrease to zero, and the limit of 21 million bitcoins [f] will be reached c. Their numbers are being released roughly every ten minutes and the rate at which they are generated would drop by half every four years until all were in circulation.

A wallet stores the information necessary to transact bitcoins. While wallets are often described as a place to hold [60] or store bitcoins, [61] due to the nature of 147 million bitcoin wiki system, bitcoins are inseparable from the blockchain transaction ledger.

A better way to describe a wallet is something that "stores the digital credentials for your bitcoin holdings" [61] and allows one to access and spend them. Bitcoin uses public-key cryptographyin which two cryptographic keys, one public and one private, are generated. There are three modes which wallets can operate in.

They have an inverse relationship with regards to trustlessness and computational 147 million bitcoin wiki. Third-party internet services called online wallets offer similar 147 million bitcoin wiki but may be easier to use. In this case, credentials to access funds are stored with the online wallet provider rather than on the user's hardware. A malicious provider or a breach in server security may cause entrusted bitcoins to be stolen.

An example of such a security breach occurred with Mt. Physical wallets store offline the credentials necessary to spend bitcoins. Another type of wallet called a hardware wallet keeps credentials offline while facilitating transactions. The first wallet program — simply named "Bitcoin" — was released in by Satoshi Nakamoto as open-source code.

While a decentralized system cannot have an "official" implementation, Bitcoin Core is considered by some to be bitcoin's preferred implementation. Bitcoin was designed not to need a central authority [5] and the bitcoin network is considered to be decentralized. In mining pool Ghash.

The pool has voluntarily capped their hashing power at Bitcoin is pseudonymousmeaning that funds are not tied to real-world entities but rather bitcoin addresses. Owners of bitcoin addresses are not explicitly identified, but all transactions on the blockchain are public.

In addition, transactions can be linked to individuals and companies through "idioms of use" e. To heighten financial privacy, a new bitcoin address can be generated for each transaction. Wallets and similar software technically handle all bitcoins as equivalent, establishing the basic level of fungibility. Researchers have pointed out that the history of each bitcoin is registered and publicly available in the blockchain ledger, and that some users may refuse to accept bitcoins coming from controversial transactions, which would harm bitcoin's fungibility.

The blocks in the blockchain were originally limited to 32 megabyte in size. The block size limit of one megabyte was introduced by Satoshi Nakamoto in147 million bitcoin wiki an anti-spam measure. On 24 August at block, Segregated Witness SegWit went live, introducing a new transaction format where signature data is separated and known as the witness. The 147 million bitcoin wiki replaced the block size limit with a limit on a new measure called block weightwhich counts non-witness data four times as much as 147 million bitcoin wiki data, 147 million bitcoin wiki allows a maximum weight of 4 megabytes.

Bitcoin is a digital asset designed by 147 million bitcoin wiki inventor, Satoshi Nakamoto, to work as a currency. 147 million bitcoin wiki question whether bitcoin is a currency or not is still disputed. According to research produced by Cambridge Universitythere were between 2. The number of users has grown significantly sincewhen there wereto 1. Inthe number of merchants accepting bitcoin exceededReasons for this fall include high transaction fees due to bitcoin's scalability issues, long transaction times and a rise in value making consumers unwilling to spend it.

Merchants accepting bitcoin ordinarily use the services of bitcoin payment service providers such as BitPay or Coinbase. When a customer pays in bitcoin, the payment service provider accepts the bitcoin on behalf of the merchant, converts it to the local currency, and sends the obtained amount to merchant's bank account, charging a fee for 147 million bitcoin wiki service.

Bitcoins can be bought on digital currency exchanges. According to Tony Gallippia co-founder of BitPay"banks are scared to deal with bitcoin companies, even if they really want to". In a report, Bank of America Merrill Lynch stated that "we believe bitcoin can become a major means of payment for e-commerce and may emerge as a serious competitor to traditional money-transfer providers. Plans were announced to include a bitcoin futures option on the Chicago Mercantile Exchange in Some Argentinians have bought bitcoins to protect their savings against 147 million bitcoin wiki inflation or the possibility that governments could confiscate savings accounts.

Bitcoin [ note 5 ] is an online payment system invented by Satoshi Nakamoto[ note 6 ] who published his invention in[ 12 ] and released it as open-source software in Bitcoins are created as a reward for payment processing work in which users offer their computing power to verify and record payments into the public ledger.

This activity is called mining and is rewarded by transaction fees and newly created bitcoins. The European Banking Authority [ 28 ] and other sources [ 14 ]: The use of bitcoin 147 million bitcoin wiki criminals has attracted the attention of financial regulators, [ 29 ] legislative bodies, [ 30 ] law enforcement, [ 31 ] and media.

As of [update]the criminal activities centered around theft and black markets. Officials in countries such as the United States also recognized that bitcoin can provide legitimate financial 147 million bitcoin wiki to customers. The block chain is a public ledger that records bitcoin transactions.

A novel solution accomplishes this without any trusted central authority: Network nodes can validate transactions, add them to their copy of the ledger, and then broadcast these ledger additions to other nodes.

147 million bitcoin wiki six times per hour, a new group of accepted transactions, a block, is created, added to the block chain, and quickly published to all nodes.

This allows bitcoin software to determine when a particular bitcoin 147 million bitcoin wiki has been spent, which is necessary in order to prevent double-spending in an environment without central oversight. Whereas a conventional ledger records the transfers of actual bills or promissory notes that exist apart from it, the block chain is the only place that bitcoins can be said to exist in the form of unspent outputs of transactions.

The unit of account of the bitcoin system is bitcoin. Named in homage to bitcoin's creator, a satoshi is the smallest multiple of bitcoin representing 0.

A microbitcoin is sometimes referred to as a bit. Ownership of bitcoins implies that a user can spend bitcoins associated with a specific address. To do so, a payer must digitally sign the transaction using the corresponding private key. Without knowledge of the private key the transaction cannot be signed and bitcoins cannot be spent. The network verifies the signature using the public key. A transaction must have one or more inputs.

For the transaction to be valid, every input must be an unspent output of a previous transaction. Every input must be digitally signed. The use of multiple inputs corresponds to the use of multiple coins in a cash transaction. A transaction can also have multiple outputs, allowing one to make multiple payments in one go. 147 million bitcoin wiki transaction output can be specified as an arbitrary multiple of satoshi. Similarly as in a cash transaction, the sum of inputs coins used to pay can exceed the intended 147 million bitcoin wiki of payments.

In such case, an additional output is used, returning the change back to the payer. To send money to a bitcoin address, users can click links on webpages; this is accomplished with a provisional Bitcoin URI scheme using a template registered with IANA.

Mobile clients recognize Bitcoin URIs in QR codesso that the user does not have to type the bitcoin address and amount in manually. The QR code is generated from the user input based on the payment amount. The QR code is displayed on the mobile device screen and can be scanned by a second mobile device.

Mining is a record-keeping service. A new block contains information that "chains" it to the previous block thus giving the block chain its name. It is a cryptographic hash of the previous block, using the SHA hashing algorithm.

A new block must also contain a so-called proof-of-work. The proof-of-work consists of a number called a difficulty target and a number called a nonce 147 million bitcoin wiki, which is jargon for "a number used only once".

Miners have to find a nonce that yields a hash of the new block numerically smaller than the number provided in the difficulty target. When the new block is created and distributed 147 million bitcoin wiki the network, every network node can easily verify the proof. The fact that the hash of the new block is smaller than the difficulty target serves as a proof that this tedious work has been done, hence the name "proof-of-work".

By changing the difficulty target number, the average time required to find a nonce can be shortened or extended A smaller number reduces the range of accepted nonces and increases the time required. The bitcoin system adjusts the difficulty target number every blocks 147 million bitcoin wiki that the average time the entire network needs to find a nonce always remains about ten minutes.

In this way the bitcoin protocol ensures that it will always take about ten minutes to add a new block regardless of the size of the network or the sophistication of the mining hardware it employs. The proof-of-work system alongside the chaining of blocks makes modifications of the block chain extremely hard as an attacker must modify all subsequent blocks in order for modifications of one block to be accepted.

As new blocks are mined all the time, the difficulty of modifying a block increases as time passes and the number of subsequent blocks increases. The environmental cost of mining includes the generation of electricity.

Even if all miners used energy efficient processes, the combined electricity consumption would be 1. As of [update]it has become common for miners 147 million bitcoin wiki join organized mining pools[ 44 ] which are used primarily to reduce variance. The reward is then split among the members creating a more steady stream of income without necessarily lowering the total expected amount of rewards for each miner when averaged over time, although a 147 million bitcoin wiki may be charged for the service.

The successful miner finding the new block is rewarded with newly created bitcoins and transaction fees. To claim the reward, a special transaction called a coinbase is included with the processed payments. The bitcoin protocol specifies that the reward for adding a block will be halved approximately every four years. Eventually, the reward will be removed entirely when an arbitrary limit of 21 million bitcoins is reached c.

Paying a transaction fee is optional, but may speed up confirmation of the transaction. Fees are 147 million bitcoin wiki on the storage size of the transaction generated, which in 147 million bitcoin wiki is dependent on the number of inputs used to create the transaction.

Furthermore, priority is given to older unspent inputs. A wallet stores the information necessary to transact bitcoins. While wallets are often described as a place to hold [ 54 ] or store bitcoins, [ 55 ] due to the nature of the system, bitcoins are inseparable from the block chain transaction ledger. Perhaps a better way to describe a wallet is something that "stores the digital credentials for your bitcoin holdings" [ 55 ] and "allows you to access and spend them". Bitcoin uses public-key cryptographyin which two cryptographic keys, one public and one private, are generated.

There are several types of wallet. Software wallets connect to the network and allow spending bitcoins in addition to holding the credentials that prove ownership. Others are simply paper printouts. Another type of wallet called a hardware wallet keeps credentials offline while facilitating transactions.

The first wallet program, called Bitcoin-Qt, was released in by Satoshi Nakamoto as open-source code. Bitcoin-Qt, also called Satoshi client, is sometimes referred to as the reference client because it serves to define the bitcoin protocol and acts as a standard for other implementations.

Privacy is achieved by not identifying owners of bitcoin addresses while making other transaction data public. Bitcoin users are not identified by name, but transactions can be linked to individuals and companies. Users concerned about privacy can use so-called mixing services that swap coins they 147 million bitcoin wiki for coins with different transaction histories. Wallets and similar software technically handle bitcoins as equivalent, establishing the basic level of fungibility.

Researchers have pointed out that the history of every single bitcoin is registered and publicly available in the block chain ledger, and that some users may refuse to accept bitcoins coming from controversial transactions, which would harm bitcoin's fungibility. Bitcoin was invented by Satoshi Nakamoto, [ note 6 ] who published his invention on 31 October in a research paper called "Bitcoin: A Peer-to-Peer Electronic Cash 147 million bitcoin wiki.

Bitcoin is often called the first cryptocurrency [ 19 ] although prior proposals existed. One of the first supporters, adopters, contributor to bitcoin and receiver 147 million bitcoin wiki the first bitcoin transaction was programmer Hal Finney. Finney downloaded the bitcoin software the day it was released, and received 10 bitcoins from Nakamoto in the world's first bitcoin transaction.

Other early supporters were Wei Dai, creator of bitcoin 147 million bitcoin wiki b-moneyand Nick Szabo, creator of bitcoin predecessor bit gold. Inan exploit in an early bitcoin client was found that allowed large numbers of bitcoins to be created.

Based on bitcoin's open source code, other cryptocurrencies started to emerge in In Marcha technical 147 million bitcoin wiki caused a fork in the block chain, with one half of the network adding blocks to one version of the chain and the other half adding to another.

For six hours two bitcoin networks operated at the same time, each with its own version of the transaction history. The core developers called for a temporary halt to transactions, sparking a sharp sell-off.

Normal operation was restored when the majority of the network downgraded to version 0. In some mainstream websites began accepting bitcoins. In OctoberChinese internet giant Baidu had allowed clients of website security services to pay with bitcoins. Gox and the Europe-based Bitstamp to become the largest bitcoin trading exchange by trade volume. As of [update] mining had become quite competitive and was compared to an arms race as ever-more-specialized technology was being utilized.

The most efficient mining hardware makes use of custom 147 million bitcoin wiki application-specific integrated circuitswhich outperform general purpose CPUs and also use less power.

In the US two men were arrested in January on charges of money-laundering using bitcoins; one was Charlie Shremthe head of now defunct bitcoin exchange BitInstant and a vice chairman of the Bitcoin Foundation. Shrem allegedly allowed the other arrested party to purchase large quantities of bitcoins for use on black-market websites. In early Februaryone of the largest bitcoin exchanges, Mt.

Gox[ ] suspended withdrawals citing technical issues. Gox had filed for bankruptcy protection in Japan amid reports thatbitcoins had been stolen. The Gathering cards, [ ] Mt. Gox had once been the dominant bitcoin exchange but its popularity had waned as users experienced difficulties withdrawing funds. On June 18,it was announced that bitcoin payment service provider BitPay would become the new sponsor of St.

Petersburg Bowl under a two-year deal, renamed the Bitcoin St. Bitcoin was to be 147 million bitcoin wiki for ticket and concession sales at the game as part of the sponsorship, and the sponsorship itself was also paid for using bitcoin. Less than one year after the collapse of Mt.