Virtual servers, virtual software, virtual storage: they're virtually rewriting job descriptions for IT practitioners. The development of IT is predicated on reinvention, and this trait can still take some getting used to. The interconnectness of enterprise computing means that small changes can cause big repercussions for existing practice models. Virtualisation in its various forms is cited as a 'disruptive technology', but such buzzwords fail to take account of the knock-on effects on the IT personnel tasked with making it work. This seems anomalous, because virtualisation hasn't just appeared from nowhere. Market-watchers had long predicted that it would be the highest-impact trend affecting enterprise computing infrastructure and operations, transforming how IT is planned, procured, deployed, managed, and accounted for. As a result, some standard IT working practices are now subject to major change. Both hardware and software can be 'virtualised' but it is reasonable to assert that the concept is driven by software, embracing both system software (operating systems) and applications; indeed, some pundits suggest that virtualisation has blurred the distinctions between the two categories.