Cryptocurrency is a digital currency. it is also called a virtual currency. it is a digital asset that handles its transactions using cryptography, cryptography is used impenetrably and confirms the transactions.In many countries, cryptocurrencies are used as alternative currencies. Bitcoin was added in 2009 as the first decentralized cryptocurrency. After that, many different cryptocurrencies came onto the market. These are usually known as Altcoins. These currencies use decentralized management as a counterweight to centralized digital money and central banking systems.Distributed management uses Bitcoin’s blockchain transaction database like a paid ledger. An encryption device generates decentralized cryptocurrency at a predefined price, which is communicated to the public. In centralized banking and the Federal Reserve System, boards of directors or governments manage the granting of currency through printing units of cash, and the exchange is carried out with digital bankbooks. However, in a decentralized cryptocurrency, companies or governments cannot produce new entities or provide support to various companies, banks, or companies that hold an asset.Satoshi Nakamoto Group created the underlying technical gadget for decentralized cryptocurrencies. Almost a thousand cryptocurrencies were created by September 2017, most of them comparable to Bitcoin. In cryptocurrency systems, security, integrity and general ledgers are maintained with the help of a team of mutually suspicious parties known as miners, whereby the general public is validated by the use of their computer systems and timestamp transactions are maintained by specific timestamp scheme. Miners, in order to preserve the security of a cryptocurrency ledger for economic reasons.Most cryptocurrencies are constantly minimizing the production of currency, capping the entire amount of currency in circulation and mimicking valuable metals. Unlike ordinary currencies, which are held via currency institutions, such as holding cash in stock, cryptocurrencies are difficult to seize by law enforcement. This issue is due to the use of cryptographic technologies. Law enforcement officials faced this trouble in the Silk Road case, in which Ulbricht’s Bitcoin stash was “encrypted”. Crypto-currencies like Bitcoin are pseudonyms, although add-ons such as Zerocoinhave been suggested to provide authentic anonymity. Some unknown Person or human beings used the title Satoshi Nakamoto and added Bitcoin in 2009 , the first digital currency. SHA-256, a cryptographic hash function , was used as work scheme in it. Namecoin used to be situated In April 2011. Litecoin used to be released,in October 2011, Scrypt was the hash function in it. cryptocurrency, Peercoin used hybrid as work proof. IOTA did not use blockchain, it uses the tangle. Built on a customized blockchain, The Divi Project permits effortless buying and selling between currencies from the wallet and the ability to use non-publicly identifiable information for transactions. Afterwards many unique cryptocurrencies have been created, however only few have been successful, as they had been lack of technical innovations.The first bitcoin ATM used to be installed in Texas, USA on February 20, 2014,by the creator of Robocoin , Jordan kelley.This ATM was identical to bank ATMs however it studied the identifications such as passport or driver license of the user with the help of scanners. Almost 1574 bitcoin ATMs had been mounted in distinct countries in 2017 with the common of 3 ATMs had been hooked up per day in 2017.The legal stature of cryptocurrencies deviate heavily from country to country and is still enduring in many of them. Although some countries have clearly allowed their use and trade, others have forbidden it. Besides, various government institutes have restricted bitcoins differently. In 2014 China Central Bank prohibited the treatment of bitcoins by financial institutions in China.In Russia, however, cryptocurrencies are legal, although it is criminal to use other currency to buy goods except for Russian ruble.The United States Internal Revenue Service allowed bitcoin to be subject to capital gains tax, on March 25,2014 this ruling clarified the legality of bitcoin.