Google is to launch a new operating system, in its most direct challenge yet to the dominance of Microsoft. Google Chrome OS will be a development of its Chrome web browser. The search giant initially aims to install the new system on small, low-cost computers known as netbooks, which are currently outselling more powerful personal computers. Google said that it believed the software would eventually be used on PCs as well. The move is likely to intensify the rivalry between Google and Microsoft, whose Windows operating system is used on the majority of the worlds personal computers. Operating systems help to run and control the basic functions of a computer.