Cloud computing can bring important benefits to both organisations and individuals. Perhaps the most obvious benefit is cost reduction. On-site ICT facilities are generally over-provisioned to allow for future growth or spikes in demand. In a data centre run by a cloud supplier, different clients will need computing resources at different times and provision does not need to be made for individual demand peaks: instead, cloud providers can quickly re-allocate resources away from those who currently need less towards those who need more. Server utilisation rates are therefore much higher and the resulting lower costs can be passed on to cloud customers. Due to this aggregation of demand, cloud suppliers also benefit from economies of scale, saving on purchasing and operating costs, including the cost of maintaining and upgrading hardware and software. The result is that four out of every five companies adopting cloud computing were able to reduce costs by 10% to 20%.