A crypto currency (or Known currency BitCoin) is a digital asset designed to work as a medium of exchange that uses cryptography to secure its transactions, to control the creation of additional units, and to verify the transfer of assets. Crypto currencies are classified as a subset of digital currencies and are also classified as a subset of alternative currencies and virtual currencies. There is more than 1500 crypto currencies are there. A growth is unbelievable in this sector so people are investing after the notification of government. In some currency there was more than 500 % growth. A article publish that Mr. Amitabh Bachhan Invest around 1.65 Cr. in 2015 in Bit Coin and his worth was 112 Cr. in Mid of December. There was lots of more example who gain and who lose the money in this sector. You can directly invest thru your regular bank as you do in mutual fund or SIP. The legal status of crypto currencies varies substantially from country to country and is still undefined or changing in many of them .China Central Bank banned the handling of Bitcoins by financial institutions in China during an extremely fast adoption period in early . There are several cryptographic technologies that make up the essence of Bitcoin. First is public key cryptography. Each coin is associated with its current owner’s public ECDSA key. When you send some Bitcoins to someone, you create a message (transaction), attaching the new owner’s public key to this amount of coins, and sign it with your private key. When this transaction is broadcast to the Bitcoin network, this lets everyone know that the new owner of these coins is the owner of the new key. Your signature on the message verifies for everyone that the message is authentic. The complete history of transactions is kept by everyone, so anyone can verify who is the current owner of any particular group of coins. The first decentralized crypto currency, Bitcoin, was created in 2009 by pseudonymous developer Satoshi Nakamoto. It used SHA-256, a cryptographic hash function, as its proof-of-work scheme.In April 2011, Namecoin was created as an attempt at forming a decentralized DNS, which would make internet censorship very difficult. Soon after, in October 2011, Litecoin was released. It was the first successful crypto currency to use scrypt as its hash function instead of SHA-256. Another notable crypto currency, Peer coin was the first to use a proof-of-work/proof-of-stake hybrid. IOTA was the first crypto currency not based on a blockchain, and instead uses the Tangle. Built on a custom blockchain, The Divi Project allows easier exchanges between currencies from within the walletand offers the ability to use personal identifying information for transactions. Many other crypto currencies have been created though few have been successful, as they have brought little in the way of technical innovation. On 6 August 2014, the UK announced its Treasury had been commissioned to do a study of crypto currencies, and what role, if any, they can play in the UK economy. The study was also to report on whether regulation should be considered. Block to the block chain is difficult, requiring time and processing power to accomplish. The incentive to put forth this time and electricity is that the person who manages to produce a block gets a reward. This reward is two-fold. First, the block producer gets a bounty of some number of Bitcoins, which is agreed-upon by the network. (Currently this bounty is 25 Bitcoins; this value will halve every 210,000 blocks.) Second, any transaction fees that may be present in the transactions included in the block, get claimed by the block producer. When the block chain after the transaction has become long enough, it becomes near-impossible for another branch to overcome it, and so people can start accepting the transaction as true. This is why ‘blocks’ also serve as ‘confirmations’ for a transaction. Even if another branch does overcome the one with the transaction, most of the blocks will have been generated by people who have no affiliation with the sender of the coins, as a large number of people are working to generate blocks. Since transactions are broadcasted to all nodes in the network, these blocks are just as likely to contain the transaction as the blocks in the previously-accepted branch. Bitcoin relies on the fact that no single entity can control most of the CPU power on the network for any significant length of time, since, if they could, they would be able to extend any branch of the tree they chose, and faster than any other branch can be extended, making it the longest branch, and then permanently controlling which transactions appear in it. A wallet stores the information necessary to transact Bitcoins. While wallets are often described as a place to hold or store Bitcoins due to the nature of the system, Bitcoins are inseparable from the block chain transaction ledger. A better way to describe a wallet is something that “stores the digital credentials for your Bitcoin holdings” and allows one to access (and spend) them. Bitcoin uses public-key cryptography. A wallet stores the information necessary to transact Bitcoins. While wallets are often described as a place to hold or store Bitcoins, due to the nature of the system, Bitcoins are inseparable from the block chain transaction ledger. A better way to describe a wallet is something that “stores the digital credentials for your Bitcoin or other Crypto currency holdings. Before investing and making fast money take an advice from experts.