Bitcoin is a cryptocurrency, a digital asset designed to work as a medium of exchange that uses cryptography to control its creation and management, rather than relying on central authorities. It was invented and implemented by the presumed pseudonymous Satoshi Nakamoto, who integrated many existing ideas from the cypherpunk community. Over the course of bitcoin's history, it has undergone. In February the world's largest bitcoin exchange, Mt. Gox, declared bankruptcy. The company stated that it had lost nearly $ million of their customers' bitcoins likely due to theft. This was equivalent to approximately , bitcoins, or about 7% of all the bitcoins in existence. The price of a bitcoin fell from a high of about. 29 rows · This is a list of Wikipedia articles about for-profit companies with notable commercial .
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Gemini described the product as a stablecoin which maintains a 1-to-1 peg with the American dollar. On October 3, it was announced that Gemini had obtained digital asset insurance covering tokens and coins held on its exchange. Bloomberg Markets reported that the insurance had been brokered by Aon , a London based public risk consulting company, and underwritten by a consortium of global underwriters. In May , a partnership was announced with Samsung whereby Samsung smartphone users could link their Samsung Blockchain Wallets to their Gemini accounts to view balances and transfer crypto.
Gemini launched an out-of-home ad campaign around Manhattan in January The Wall Street Journal reported that the ad campaign was directed at providing wary investors with a "Shelter in a storm" that is fully regulated and compliant with existing American cryptocurrency regulation.
The site's primary challenge has been remaining online at times of excessively high volumes, a relatively common occurrence for any website receiving an unusual amount of traffic.
Gemini was showing a " gateway time-out" message, and the status page showed "Systems are currently experiencing degraded performance. From Wikipedia, the free encyclopedia. Redirected from Gemini digital currency exchange.
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See also: legality of bitcoin by country or territory. Money Laundering in Digital Currencies. June Retrieved 11 January Page number assigned by Google Books. Paris: Financial Action Task Force. Archived from the original PDF on 11 February CRC Press. The Wall Street Journal. Retrieved 11 September Archived from the original on 23 March Retrieved 9 January The Tico Times. Archived from the original on 31 December Retrieved 11 December Archived from the original on 14 April United States Department of Homeland Security.
Financial Times. The New York Times. Gox abandons rebuilding plans and files for liquidation: WSJ". Most cryptocurrencies are designed to gradually decrease production of that currency, placing a cap on the total amount of that currency that will ever be in circulation. The validity of each cryptocurrency's coins is provided by a blockchain. A blockchain is a continuously growing list of records , called blocks , which are linked and secured using cryptography.
It is "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way". Once recorded, the data in any given block cannot be altered retroactively without the alteration of all subsequent blocks, which requires collusion of the network majority.
Blockchains are secure by design and are an example of a distributed computing system with high Byzantine fault tolerance. Decentralized consensus has therefore been achieved with a blockchain. Cryptocurrencies use various timestamping schemes to "prove" the validity of transactions added to the blockchain ledger without the need for a trusted third party.
The first timestamping scheme invented was the proof-of-work scheme. The most widely used proof-of-work schemes are based on SHA and scrypt. The proof-of-stake is a method of securing a cryptocurrency network and achieving distributed consensus through requesting users to show ownership of a certain amount of currency.
It is different from proof-of-work systems that run difficult hashing algorithms to validate electronic transactions. The scheme is largely dependent on the coin, and there's currently no standard form of it. Some cryptocurrencies use a combined proof-of-work and proof-of-stake scheme. In cryptocurrency networks, mining is a validation of transactions. For this effort, successful miners obtain new cryptocurrency as a reward.
The reward decreases transaction fees by creating a complementary incentive to contribute to the processing power of the network. Thus the value of the currency obtained for finding a hash often does not justify the amount of money spent on setting up the machines, the cooling facilities to overcome the heat they produce, and the electricity required to run them.
Some miners pool resources , sharing their processing power over a network to split the reward equally, according to the amount of work they contributed to the probability of finding a block. A "share" is awarded to members of the mining pool who present a valid partial proof-of-work. Some Chinese miners have since relocated to Canada. In March , the city of Plattsburgh in upstate New York put an month moratorium on all cryptocurrency mining in an effort to preserve natural resources and the "character and direction" of the city.
An increase in cryptocurrency mining increased the demand for graphics cards GPU in Miners regularly buy up the entire stock of new GPU's as soon as they are available. Nvidia has asked retailers to do what they can when it comes to selling GPUs to gamers instead of miners. A cryptocurrency wallet stores the public and private "keys" or "addresses" which can be used to receive or spend the cryptocurrency.
With the private key, it is possible to write in the public ledger, effectively spending the associated cryptocurrency. With the public key, it is possible for others to send currency to the wallet.
Bitcoin is pseudonymous rather than anonymous in that the cryptocurrency within a wallet is not tied to people, but rather to one or more specific keys or "addresses". Still, cryptocurrency exchanges are often required by law to collect the personal information of their users.
Additions such as Zerocoin , Zerocash and CryptoNote have been suggested, which would allow for additional anonymity and fungibility. Most cryptocurrency tokens are fungible and interchangeable. However, unique non-fungible tokens also exist. Such tokens can serve as assets in games like CryptoKitties. Cryptocurrencies are used primarily outside existing banking and governmental institutions and are exchanged over the Internet.
Proof-of-work cryptocurrencies, such as bitcoin, offer block rewards incentives for miners. There has been an implicit belief that whether miners are paid by block rewards or transaction fees does not affect the security of the blockchain, but a study suggests that this may not be the case under certain circumstances. The rewards paid to miners increase the supply of the cryptocurrency.
By making sure that verifying transactions is a costly business, the integrity of the network can be preserved as long as benevolent nodes control a majority of computing power. The verification algorithm requires a lot of processing power, and thus electricity in order to make verification costly enough to accurately validate public blockchain.
Not only do miners have to factor in the costs associated with expensive equipment necessary to stand a chance of solving a hash problem, they further must consider the significant amount of electrical power in search of the solution.
Generally, the block rewards outweigh electricity and equipment costs, but this may not always be the case. The current value, not the long-term value, of the cryptocurrency supports the reward scheme to incentivize miners to engage in costly mining activities. Some sources claim that the current bitcoin design is very inefficient, generating a welfare loss of 1. The main source for this inefficiency is the large mining cost, which is estimated to be Million USD per year.
However, the efficiency of the bitcoin system can be significantly improved by optimizing the rate of coin creation and minimizing transaction fees. Another potential improvement is to eliminate inefficient mining activities by changing the consensus protocol altogether. Transaction fees for cryptocurrency depend mainly on the supply of network capacity at the time, versus the demand from the currency holder for a faster transaction. For ether , transaction fees differ by computational complexity, bandwidth use, and storage needs, while bitcoin transaction fees differ by transaction size and whether the transaction uses SegWit.
Some cryptocurrencies have no transaction fees, and instead rely on client-side proof-of-work as the transaction prioritization and anti-spam mechanism. Cryptocurrency exchanges allow customers to trade cryptocurrencies for other assets, such as conventional fiat money , or to trade between different digital currencies.
Atomic swaps are a mechanism where one cryptocurrency can be exchanged directly for another cryptocurrency, without the need for a trusted third party such as an exchange.
The kiosk installed in Austin, Texas, is similar to bank ATMs but has scanners to read government-issued identification such as a driver's license or a passport to confirm users' identities.
An initial coin offering ICO is a controversial means of raising funds for a new cryptocurrency venture.
An ICO may be used by startups with the intention of avoiding regulation. However, securities regulators in many jurisdictions, including in the U. In an ICO campaign, a percentage of the cryptocurrency usually in the form of "tokens" is sold to early backers of the project in exchange for legal tender or other cryptocurrencies, often bitcoin or ether.
According to PricewaterhouseCoopers , four of the 10 biggest proposed initial coin offerings have used Switzerland as a base, where they are frequently registered as non-profit foundations. The Swiss regulatory agency FINMA stated that it would take a "balanced approach" to ICO projects and would allow "legitimate innovators to navigate the regulatory landscape and so launch their projects in a way consistent with national laws protecting investors and the integrity of the financial system.
The legal status of cryptocurrencies varies substantially from country to country and is still undefined or changing in many of them. While some countries have explicitly allowed their use and trade,  others have banned or restricted it.
Various government agencies, departments, and courts have classified bitcoin differently. China Central Bank banned the handling of bitcoins by financial institutions in China in early In Russia, though cryptocurrencies are legal, it is illegal to actually purchase goods with any currency other than the Russian ruble.
Cryptocurrencies are a potential tool to evade economic sanctions for example against Russia , Iran , or Venezuela. Russia also secretly supported Venezuela with the creation of the petro El Petro , a national cryptocurrency initiated by the Maduro government to obtain valuable oil revenues by circumventing US sanctions. The Japanese platform Line and the Russian platform Yandex have similar prohibitions. This means bitcoin will be subject to capital gains tax. In July , the IRS started sending letters to cryptocurrency owners warning them to amend their returns and pay taxes.
As the popularity of and demand for online currencies has increased since the inception of bitcoin in ,  so have concerns that such an unregulated person to person global economy that cryptocurrencies offer may become a threat to society. Concerns abound that altcoins may become tools for anonymous web criminals. Cryptocurrency networks display a lack of regulation that has been criticized as enabling criminals who seek to evade taxes and launder money. Money laundering issues are also present in regular bank transfers , however with bank-to-bank wire transfers for instance, the account holder must at least provide a proven identity.
Transactions that occur through the use and exchange of these altcoins are independent from formal banking systems, and therefore can make tax evasion simpler for individuals. Since charting taxable income is based upon what a recipient reports to the revenue service, it becomes extremely difficult to account for transactions made using existing cryptocurrencies, a mode of exchange that is complex and difficult to track.
Systems of anonymity that most cryptocurrencies offer can also serve as a simpler means to launder money. Rather than laundering money through an intricate net of financial actors and offshore bank accounts, laundering money through altcoins can be achieved through anonymous transactions. In February the world's largest bitcoin exchange, Mt.
Gox , declared bankruptcy. Homero Josh Garza, who founded the cryptocurrency startups GAW Miners and ZenMiner in , acknowledged in a plea agreement that the companies were part of a pyramid scheme , and pleaded guilty to wire fraud in The U. The SEC's complaint stated that Garza, through his companies, had fraudulently sold "investment contracts representing shares in the profits they claimed would be generated" from mining.
Tether indicates that it is building a new core for its primary wallet in response to the attack in order to prevent the stolen coins from being used. Properties of cryptocurrencies gave them popularity in applications such as a safe haven in banking crises and means of payment, which also led to the cryptocurrency use in controversial settings in the form of online black markets , such as Silk Road.
In the year following the initial shutdown of Silk Road, the number of prominent dark markets increased from four to twelve, while the amount of drug listings increased from 18, to 32, Darknet markets present challenges in regard to legality. Cryptocurrency used in dark markets are not clearly or legally classified in almost all parts of the world.
In the U. Cryptocurrencies have been compared to Ponzi schemes , pyramid schemes  and economic bubbles ,  such as housing market bubbles. While cryptocurrencies are digital currencies that are managed through advanced encryption techniques, many governments have taken a cautious approach toward them, fearing their lack of central control and the effects they could have on financial security.
He cautioned that virtual currencies pose a new challenge to central banks' control over the important functions of monetary and exchange rate policy. Cryptocurrency mining consumes significant quantities of electricity and has a large associated carbon footprint.
Bitcoin, Ethereum, Litecoin, and Monero were estimated to have added 3 to 15 million tonnes of carbon dioxide emissions to the atmosphere in the period from 1 January to 30 June There are also purely technical elements to consider. For example, technological advancement in cryptocurrencies such as bitcoin result in high up-front costs to miners in the form of specialized hardware and software.
Additionally, cryptocurrency private keys can be permanently lost from local storage due to malware, data loss or the destruction of the physical media. This prevents the cryptocurrency from being spent, resulting in its effective removal from the markets.
The cryptocurrency community refers to pre-mining, hidden launches, ICO or extreme rewards for the altcoin founders as a deceptive practice. Paul Krugman , winner of the Nobel Memorial Prize in Economic Sciences , has repeated numerous times that it is a bubble that will not last  and links it to Tulip mania.
Fink called bitcoin an 'index of money laundering '. It covers studies of cryptocurrencies and related technologies, and is published by the University of Pittsburgh. The journal encourages authors to digitally sign a file hash of submitted papers, which will then be timestamped into the bitcoin blockchain. Authors are also asked to include a personal bitcoin address in the first page of their papers.
Cryptocurrencies make tracking donations easier and have the potential to allow donors to see how their money is used financial transparency. From Wikipedia, the free encyclopedia. See also: History of bitcoin.