now on bbc news: bitcoin has become big business and a major talking point around the globe. our world investigates kazakhstan�*s cryptocurrency boom. bitcoin is a growing part of modern day life. newsreader: let's start though by talking about bitcoin. - newsreader: it is a virtual currency that only _ exists on the internet. newsreader: the value | of bitcoin has soared more than tenfold this year. everyone wants a piece of the pie. but there is one place where the boom has hit big. within two years, kazakhstan has become second only to the us as a global leader in bitcoin mining. the complex technological process that powers this digital money.