What is bitcoin?
Bitcoin is the most widely used cryptocurrency in the worldbut there are more than 700. Ethereum, ripple, litecoin and monero are other examples of currencies that work similarly.
Cryptocurrencies, with some variations, are exchanged for currencies such as dollars or euros. Anyone can buy or sell a good using bitcoins, as long as a counterparty agrees to make the transaction.
Like any other currency, cryptocurrencies can also be changed. One bitcoin is currently worth €1,345 and $1,471. Its value is constantly fluctuating according to supply and demand.
The most immediate difference to the euro or dollar is the absence of physical support. There are no coins or banknotes in circulation. We do not pay by check or bank card in bitcoin.
A bitcoin (like ether, litecoin, etc.) is a sequence of numbers stored on a computer. Its value is not indexed to gold, any more than conventional currency, nor is it controlled by a central body.
However, despite appearances, security and transparency are the main properties of crypto-currencies. So far, no one has violated the control procedures (read below). The main danger lies in the reliability of intermediaries.
How does it work?
Cryptocurrencies are all based on blockchain, or blockchains, which refers to a relatively simple mechanism.
Get a database. Allow anyone to make changes to this database, on the sole condition of declaring themselves a “member”. Create a very long and very complex control procedure that must be performed every time a certain number (“block”) of changes is requested. This procedure is carried out not by a controller, but by all voluntary “members”. If validated, the “block” of changes is dated and added to the rest of the registry. Finally, allow everyone to read the register, and you have a blockchain database (see opposite an application diagram for crypto-currencies).
The three main innovations of this system are self-management (no central body), security (prevention methods are more complicated sabotage) and transparency. Needless to say, everything happens on a computerized scale, without keeping track of paper operations.

Bitcoin and crypto-currencies, new digital coinsBlockChain UK
How to get cryptocurrencies?
We will not give an opinion here of interest, whether speculative or not, in crypto-currencies. For this, read our January 7 issue (stock number 2224).
However, taking an interest in the concrete approach makes it possible to better understand the phenomenon. To have bitcoins (or another cryptocurrency), you need to sell something to someone who will pay you in bitcoins, or directly convert euros to bitcoins.
Both cases require creating a “wallet”, which is an address (a sequence of numbers) accessed with a password. These two codes are created according to an algorithm defined at the birth of the currency. There is no limit to the number of users, and the process is anonymous. You can get a bitcoin address and password for free and easily on the Internet (for example at BitAddress.org).
Then, it is necessary to call a mediator. Here again, the possibilities are many. It is possible to go through an exchange platform similar to a broker, or to download software that will show the balance and pay in different ways. Most of these brokers charge commissions and should be chosen carefully because many have gone bankrupt.
SPREAD
Outside the classic economic circuit One of the main characteristics of cryptocurrencies is the absence of a central control body. They fluctuate according to supply and demand, and therefore do not require central banks or clearing houses. Making money is automatic and based on rules established at the beginning. It is, for example, expected that a maximum of 21 million bitcoins will be issued, at a slower rate that depends on the number of transactions. Currently 16 million are in circulation. Although it is difficult to estimate, the date of issuance of the last bitcoin will be around 2140. There is no official process for destroying the currency.