Cloud technology may not be a household term for everyone, but it's already moved well past the concept stage, with cloud computing and cloud storage. A quick example: the iCloud, which enables us to backup our iPhone data to Apple's servers, and retrieve them from our computers at home and at work.

This week, thousands of people have had their heads in the clouds in London. With these technologies finding their way into almost all businesses, this year's Cloud Expo Europe has become the battlefield for leading industry players, including Amazon, Microsoft, Google and IBM.

According to Synergy Research Group, these four American technology giants control half of the 148-billion-dollar worldwide cloud business, with Amazon alone owning about a third of the global share. 

Some other companies including China's Alibaba are growing strongly, but they are still a long way from the American big four.

Other big Chinese companies, including Huawei, Lenovo and China Unicom, are also here.

Tong Siyi from China Telecom told CGTN reporters that the company is trying to create a "digital Silk Road" and contribute to China's "Belt and Road" strategy.

According to the organizer, more than 500 exhibitors, over 600 speakers from around the world attended Europe's biggest cloud show.