Bitcoin Habrahabr

Click here for cryptocurrency Links

g and government systems.

Cryptocurrencies use cryptography to secure transactions and regulate the creation of additional units. Bitcoin, the original and by far most well-known cryptocurrency, was launched in January 2009. Today there are over 1,000 cryptocurrencies available online.

Cryptocurrencies differ significantly from traditional fiat currencies. Nonetheless, you can still buy and sell them like any other asset. You can now also trade on the price movements of various cryptocurrencies via CFDs and spread betting.

Cryptocurrencies fall under the banner of digital currencies, alternative currencies and virtual currencies. They were initially designed to provide an alternative payment method for online transactions. However, cryptocurrencies have not yet been widely accepted by businesses and consumers, and they are currently too volatile to be suitable as methods of payment. As a decentralised currency, it was developed to be free from government oversite or influence, and the cryptocurrency economy is instead monitored by peer-to-peer internet protocol. The individual units that make up a cryptocurrency are encrypted strings of data that have been encoded to represent one unit.

Bitcoin is credited with being the first decentralised cryptocurrency. Like all cryptocurrencies, it’s controlled through a blockchain transaction database, which functions as a distributed public ledger. Bitcoin was created by Satoshi Nakamoto – whether the name refers to an individual or a group is unknown.

A feature of most cryptocurrencies is that they have been designed to slowly reduce production. Consequently, only a limited number of units of the currency will ever be in circulation. This mirrors commodities such as gold and other precious metals. For example, the number of bitcoins is not expected to exceed 21 million. Cryptocurrencies such as ethereum, on the other hand, work slightly differently. Issuance is capped at 18 million ethereum tokens per year, which equals 25% of the initial supply. Limiting the number of bitcoins provides ‘scarcity’, which in turn gives it value. Some claim that bitcoin’s creator actually modelled the cryptocurrency on precious metals. As a result, mining becomes more difficult over time, as the mining reward gets halved every few years until it reaches zero.

Key features of cryptocurrencies
There are a number of key principles that govern cryptocurrency use, exchange and transactions.

Cryptography
Cryptocurrencies use advanced cryptography in a number of ways. Cryptography evolved out of the need for secure communication methods in the second world war, in order to convert easily-readable information into encrypted code. Modern cryptography has come a long way since then, and in today’s digital world it’s based primarily on computer science and mathematical theory. It also draws from communication science, physics and electrical engineering.

Two main elements of cryptography apply to cryptocurrencies – hashing and digital signatures:

Hashing verifies data integrity, maintains the structure of the blockchain and encodes people’s account addresses and transactions. It also generates the cryptographic puzzles that make block mining possible.
Digital signatures allow an individual to prove that they own a piece of encrypted information without revealing that information. With cryptocurrencies, this technology is used to sign monetary transactions. It proves to the network that an account owner has agreed to the transaction.
Blockchain technology
A blockchain is the decentralised, public ledger or list of a cryptocurrency’s transactions. Completed blocks, comprised of the latest transactions, are recorded and added to the blockchain. They are stored in chronological order as an open, permanent and verifiable record. A peer-to-peer network of market participants manage blockchains, and they follow a set protocol for validating new blocks. Each ‘node’ or computer connected to the network automatically downloads a copy of the blockchain. This allows everyone to track transactions without the need for central record keeping.

Blockchain technology creates a record that can’t be changed without the agreement of the rest of the network. The blockchain concept is attributed to bitcoin’s founder, Satoshi Nakamoto. This concept has been the inspiration for other applications beyond digital cash and currency.

Block mining
Block mining is the process of attaching new transaction records as blocks to the blockchain. In the process – using bitcoin as an example – new bitcoins get produced, adding to the total number of coins in circulation. Mining requires a specific piece of software that is used to solve mathematical puzzles, and this validates the legitimate transactions which make up blocks. These blocks get added to the public ledger (blockchain) about every 10 minutes. As the software solves transactions the miner is rewarded with a set amount of bitcoins. The faster a miner’s hardware can process the mathematical problem, the more likely it is to validate a transaction and earn the bitcoin reward.