Bitcoin is a type of cryptocurrency: Balances are kept using public and private "keys," which are long strings of numbers and letters linked through the mathematical encryption algorithm that was used to create them. The public key (comparable to a bank account number) serves as the address which is published to the world and to which others may send bitcoins. The private key (comparable to an ATM PIN) is meant to be a guarded secret, and only used to authorize Bitcoin transmissions.
The very first transaction involving Bitcoin occurred between an early adopter and Nakamoto in January 2009. The first transaction in the real world is the notorious instance when a Bitcoin miner chose to buy pizza from Papa John’s. He famously spent 10,000 Bitcoins to buy two pizzas in 2010 in Florida. That transaction alone perfectly shows the dramatic change in value that Bitcoin has experienced over the years.
Our first assumption is that bitcoin will derive its value both from its use as a medium of exchange and as a store of value.  As a footnote to this assumption, it should be stated that bitcoin's utility as a store of value is dependent on its utility as a medium of exchange.  We base this in turn on the assumption that for something to be used as a store of value it needs to have some intrinsic value, and if bitcoin does not achieve success as a medium of exchange, it will have no practical utility and thus no intrinsic value and won't be appealing as a store of value.    

Bitcoin (BTC) is a cryptocurrency which is regarded as the world’s first decentralized digital currency. It was created by a pseudonymous person or persons named Satoshi Nakamoto in 2009 and has since gone on to become the world’s most popular cryptocurrency by market cap. Bitcoin is a deflationary currency whose issuance is capped at a total supply of 21 million coins. Each Bitcoin can be divided into one million units, with the smallest unit of 0.00000001 known as a satoshi in homage to its creator. The distributed public ledger that Bitcoin uses to record transactions is known as a blockchain and Bitcoin can be spent at over 100,000 online merchants and can also be held as an investment. Bitcoin is traded for fiat and other cryptocurrencies on various exchanges but can also be used to facilitate p2p transactions. Each transaction incurs a small transaction fee to cover the cost of sending Bitcoin over the blockchain ledger, with the fee going to miners tasked with keeping the network secure.
In September 2015, the establishment of the peer-reviewed academic journal Ledger (ISSN 2379-5980) was announced. It covers studies of cryptocurrencies and related technologies, and is published by the University of Pittsburgh.[239] 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.[240][241]
Because of bitcoin's decentralized nature and its trading on online exchanges located in many countries, regulation of bitcoin has been difficult. However, the use of bitcoin can be criminalized, and shutting down exchanges and the peer-to-peer economy in a given country would constitute a de facto ban.[164] The legal status of bitcoin varies substantially from country to country and is still undefined or changing in many of them. Regulations and bans that apply to bitcoin probably extend to similar cryptocurrency systems.[165]
Bitcoins can be accepted as a means of payment for products sold or services provided. If you have a brick and mortar store, just display a sign saying “Bitcoin Accepted Here” and many of your customers may well take you up on it; the transactions can be handled with the requisite hardware terminal or wallet address through QR codes and touch screen apps. An online business can easily accept bitcoins by just adding this payment option to the others it offers, like credit cards, PayPal, etc. Online payments will require a Bitcoin merchant tool (an external processor like Coinbase or BitPay). 
Full clients verify transactions directly by downloading a full copy of the blockchain (over 150 GB As of January 2018).[90] They are the most secure and reliable way of using the network, as trust in external parties is not required. Full clients check the validity of mined blocks, preventing them from transacting on a chain that breaks or alters network rules.[91] Because of its size and complexity, downloading and verifying the entire blockchain is not suitable for all computing devices.
In January 2014, Zynga[92] announced it was testing bitcoin for purchasing in-game assets in seven of its games. That same month, The D Las Vegas Casino Hotel and Golden Gate Hotel & Casino properties in downtown Las Vegas announced they would also begin accepting bitcoin, according to an article by USA Today. The article also stated the currency would be accepted in five locations, including the front desk and certain restaurants.[93] The network rate exceeded 10 petahash/sec.[94] TigerDirect[95] and Overstock.com[96] started accepting bitcoin.
In September 2015, the establishment of the peer-reviewed academic journal Ledger (ISSN 2379-5980) was announced. It covers studies of cryptocurrencies and related technologies, and is published by the University of Pittsburgh.[239] 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.[240][241]
Bitcoin's price is also quite dependent on the size of its mining network, since the larger the network is, the more difficult – and thus more costly – it is to produce new bitcoins. As a result, the price of bitcoin has to increase as its cost of production also rises. The Bitcoin mining network's aggregate power has more than tripled over the past twelve months.
The most recent exciting news in Bitcoin history began in November 2017 and led to the current all-time high for the cryptocurrency. In 2017, Bitcoin went from trading at just over $900 to about $20,000. This was a journey with many ups and downs along the way, a drop in trading volumes due to the People’s Bank of China tightening oversight of Bitcoin exchanges and the U.S. Securities and Exchange Commission rejecting a Bitcoin exchange-traded fund.
^ Jump up to: a b c d "Statement of Jennifer Shasky Calvery, Director Financial Crimes Enforcement Network United States Department of the Treasury Before the United States Senate Committee on Banking, Housing, and Urban Affairs Subcommittee on National Security and International Trade and Finance Subcommittee on Economic Policy" (PDF). fincen.gov. Financial Crimes Enforcement Network. 19 November 2013. Archived (PDF) from the original on 9 October 2016. Retrieved 1 June 2014.
Jump up ^ Beikverdi, A.; Song, J. (June 2015). "Trend of centralization in Bitcoin's distributed network". 2015 IEEE/ACIS 16th International Conference on Software Engineering, Artificial Intelligence, Networking and Parallel/Distributed Computing (SNPD): 1–6. doi:10.1109/SNPD.2015.7176229. ISBN 978-1-4799-8676-7. Archived from the original on 26 January 2018.

Full clients verify transactions directly by downloading a full copy of the blockchain (over 150 GB As of January 2018).[90] They are the most secure and reliable way of using the network, as trust in external parties is not required. Full clients check the validity of mined blocks, preventing them from transacting on a chain that breaks or alters network rules.[91] Because of its size and complexity, downloading and verifying the entire blockchain is not suitable for all computing devices.
The concept of a virtual currency is still novel and, compared to traditional investments, Bitcoin doesn't have much of a longterm track record or history of credibility to back it. With their increasing use, bitcoins are becoming less experimental every day, of course; still, after eight years, they (like all digital currencies) remain in a development phase, still evolving. "It is pretty much the highest-risk, highest-return investment that you can possibly make,” says Barry Silbert, CEO of Digital Currency Group, which builds and invests in Bitcoin and blockchain companies.
The whole process is pretty simple and organized: Bitcoin holders are able to transfer bitcoins via a peer-to-peer network. These transfers are tracked on the “blockchain,” commonly referred to as a giant ledger. This ledger records every bitcoin transaction ever made. Each “block” in the blockchain is built up of a data structure based on encrypted Merkle Trees. This is particularly useful for detecting fraud or corrupted files. If a single file in a chain is corrupt or fraudulent, the blockchain prevents it from damaging the rest of the ledger.
On 6 August 2010, a major vulnerability in the bitcoin protocol was spotted. Transactions weren't properly verified before they were included in the transaction log or blockchain, which let users bypass bitcoin's economic restrictions and create an indefinite number of bitcoins.[25][26] On 15 August, the vulnerability was exploited; over 184 billion bitcoins were generated in a transaction, and sent to two addresses on the network. Within hours, the transaction was spotted and erased from the transaction log after the bug was fixed and the network forked to an updated version of the bitcoin protocol.[27] This was the only major security flaw found and exploited in bitcoin's history.[25][26] 

Though transaction fees are optional, miners can choose which transactions to process and prioritize those that pay higher fees.[67] Miners may choose transactions based on the fee paid relative to their storage size, not the absolute amount of money paid as a fee. These fees are generally measured in satoshis per byte (sat/b). The size of transactions is dependent on the number of inputs used to create the transaction, and the number of outputs.[3]:ch. 8 

Bitcoin is a new currency that was created in 2009 by an unknown person using the alias Satoshi Nakamoto. Transactions are made with no middle men – meaning, no banks! Bitcoin can be used to book hotels on Expedia, shop for furniture on Overstock and buy Xbox games. But much of the hype is about getting rich by trading it. The price of bitcoin skyrocketed into the thousands in 2017.
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