Cyber criminals were widely reported as having demanded ‘bitcoins’ in their ransom demands last week.Thousands of computers around the world were infected with ransomware on Friday with users files locked and demands for bitcoin payments to allow access.NHS hospitals, GP surgeries, pharmacies, FedEx and Spain’s main telecoms provider Telefonica were among those targetted in the cyber assault, which is though to have affected 150 countries.In Britain, the attack meant hundreds of operations were cancelled as well as patient files, test results and X-rays being unavailable – with fears the attack could start up again this week as workers return to their computers.But why did the cyber criminals demand bitcoins?And what re they?Here is everything you need to know.MORE: The criminals behind WannaCry ransomware earned a stupidly small amount of money MORE: Still running Windows XP?Here’s what to do about WannaCry ransomware Bitcoin is a decentralised digital currency, meaning neither does it exist in the physical world, nor does it have a central bank such as the Federal Reserve or the Bank of England.

Only 21 million bitcoins exist but this is not seen as a limitation because bitcoins can be broken down into smaller sub-units of bits with 1,000,000 bits in 1 bitcoin.Bitcoins can be divided up to 8 decimal places (0.000 000 01) and potentially even smaller units.There are public records that track the spending of bitcoin.However there is an element of privacy involved in the digital currency as well as it being impossible to counterfeit, immune to fraudulent chargebacks and transactions being irreversible.This, as well as the currency being global, have led to concerns that it is an attractive currency for criminals.Bitcoin was introduced in 2009 by a mysterious programmer known only as Satoshi Nakamoto, which is thought to be a pseudonym, and who has never given an interview.Previously the domain of technology-friendly libertarians, bitcoin has shot to mainstream financial attention after its value increased by up to 1,000 per cent since the start of the year.The rise of bitcoin also coincided with the tipping point of the financial crisis in Cyprus, when it was announced individual savers faced a one-off levy in order for a eurozone bailout to go ahead.

In light of governments raiding savings in this way, the prospect of a currency free from government regulation and interference suddenly becomes much more enticing.However, the US Treasury has previously made moves to apply laundering rules to virtual currencies such as bitcoin. and download a ‘wallet’ on your computer or mobile.Bitcoin uses peer-to-peer networking and digital signatures where the money supply is automated and given to servers known as ‘bitcoin miners’.Bitcoins, in blocks of 25, are awarded to these miners when their computer generates a 64-digit number from a complex algorithm.It is helpful to think of bitcoin more as a commodity being mined rather than a traditional currency of which central banks can always create more of.Yes, the most popular way is via online exchanges, or via bank transfer on websites including Coinbase.Sellers can also be found directly online or even by meeting them in person.Technically anything, although virtually no mainstream retailers currently accept them.

Blogging platform WordPress and WikiLeaks both accept bitcoin, while some sites offer gift vouchers for retailers such as Amazon.There are also websites selling electronic goods that exclusively accept bitcoin.bitcoin vps chinaThe dark side to bitcoin is how it is accepted on sites such as anonymous marketplace Silk Road, where users can buy illegal drugs such as LSD.bitcoin nvidia miningThe big question is whether bitcoin is truly a self-stabilising currency, with all the evidence so far pointing to no, with it having already shown massive fluctuations in price.sell bitcoin for audIn February 2014 a single bitcoin was worth $20, but two months later on April 10 its value crashed from $266 to $105 before returning to $160 within several hours.cara dapat bitcoin

Many mainstream economists regard bitcoin as a bubble waiting to pop, with comparisons made with Dutch tulip mania in the 17th century.Exchanges can also be vulnerable to distributed denial of service attacks, which can lower prices.bitcoin majority attackFor more information you can read the bitcoin community’s own guide to the currency.ibm bitcoin blockchainMORE: Ransomware: The new cyber threat taking your computer hostage MORE: Actress left trail of her own urine to help find her missing catA group of hackers who claimed to hold millions of iCloud accounts for ransom said on Friday they'd been paid.But one bitcoin expert says that's bogus.They demanded increasing ransoms from Apple while threatening to wipe the data from devices connected to the affected accounts if it did not.On Friday, the hackers tweeted that they had been paid US$480,000 in bitcoin.

As proof, the group posted a link showing a transaction on Blockchain.info, a popular bitcoin wallet.“We were told by our negotiator that we have come to a final agreement with Apple,” the hacking group tweeted prior to receiving the payment.However, the hackers actually tweeted out a transaction to an "internal treasury operation at a bitcoin exchange," according to Jonathan Levin, co-founder at Chainalysis, a provider of anti-money laundering software for bitcoin."Wehave positively identified that the inputs and outputs of that transaction are controlled by a single bitcoin exchange," Levin said in an email.The transaction was part of an internal money deposit process at a Korean bitcoin exchange, he said.Apple didn’t respond to a request for comment.The tech giant has said that it never suffered any such breach.The stolen login credentials that the hackers obtained appeared to come from breaches at other third-party services, Apple said.Security researchers suspect that's true, and they believe the Turkish Crime Family has exaggerated its hacking claims.