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Cambridge University Science Magazine
Advances in cloud computing technology promise a style of computing in which flexible and accessible resources are provided as a universal service over the internet. This may revolutionise the way we use computers.

The basic premise of a cloud application is that data is stored online on a remote server instead of on your personal computer. Data is stored ‘in the cloud’ – you may have no idea where it is, but it can be accessed wherever you are in the world, on any device, be that a laptop or a mobile phone. Many of us have been using cloud applications unknowingly for years; web-based tools such as Hotmail are established examples.

Cloud computing is increasingly being used to deliver services over the internet as well as providing a convenient place to store files. Companies such as Amazon, Google and Microsoft maintain vast warehouses that hold hundreds of servers that we connect to each time we use these services. They can provide all computing resources that, up to now, we have had to buy and maintain ourselves; servers, storage, software, operating systems, security and anti-virus programs. Instead of having to buy this wide range of essential kit, cloud computing allows us to rent them from big companies. This is changing computing into a utility like electricity or water, which allows us to pay only for what we use.

Small companies no longer need large capital for expensive computing facilities since resources that they need may simply be rented from a cloud provider. This has instant appeal to start-ups, removing the risk of excessive or inadequate provision of computing resources since these can now be provided on demand. A new company can start small, renting few resources in the beginning, and increase its use of the cloud with rising user demand. If the company grows so that more resources are needed, an instant upgrade is available from the cloud provider. This minimises disruption to existing users while maximising growth of the company.

But why would companies such as Google or Amazon want to let other companies use their resources? The answer is that sharing these resources among many users is economically more efficient. Not only must these online giants buy and install the facilities, they must also maintain them. Individual server usage is often as low as 15 per cent, so renting out their unused resources gives cloud providers an important new source of revenue to offset maintenance costs.

Despite the benefits for businesses and society, some see dark clouds on the horizon as concerns loom over security, privacy and control. There is the potential for unauthorised access to proprietary information and for loss of control over sensitive data. Movement of data from one country to another may raise legal issues, while server failures could have serious consequences. Amazon’s S3 cloud service was down for eight hours in July 2008; such a significant outage represented an incredible loss for hundreds of cloud client companies around the world. These issues must be addressed if cloud computing is to succeed.

Nevertheless, the vision of computing as a utility is becoming a reality. Soon we may all be accessing applications in the cloud and using it to rent resources. The internet will once again provide new possibilities for our use of computers, revolutionising the way we use them both at work and at home.

Fernando Ramos is a PhD student in the Department of Engineering