>> Bitcoin is back in the news after last week's cyber attack that's hit more than 300,000 computers since last Friday, including those belonging to Britain's health services and Spain's telecoms provider. The hackers responsible demanded the digital currency as ransom. I'm Reuters' Jemima Kelly in London, one of the world's top financial centers, where many banks have their European headquarters.
Bitcoin, as a web-based digital currency, has no headquarters and no central bank. It relies instead on a global network of computers that validate and process the transactions. The reason that hackers use Bitcoin is that it is an anonymous currency that can be sent from one anonymous wallet to another anonymous wallet.
There are new cryptocurrencies that have emerged in the last few years as people have realized that Bitcoin isn't fully anonymous. So there are currencies like Monero and Dash and Zcash that have emerged recently that have built-in anonymity, so that rather than having to go through extra steps to mask your identity when making payments with Bitcoin, you're automatically hidden.
And law enforcement agencies and security firms find it very, very difficult to track people using those currencies, whereas with Bitcoin, they can sometimes find the people behind these pseudonymous Bitcoin addresses.