There are some companies that have provided an online infrastructure service. AWS is a well known service that provides online infrastructure, which is called cloud or public cloud. Back in the year 2006, AWS officially launched the virtual machine service, which was called Elastic Computing Cloud (EC2); an online object store service, which was called Simple Storage Service (S3); and an online messaging queue service, which was called Simple Queue Service (SQS).

These services are simple enough, but from a data center management point of view, they relieve infrastructure pre-allocation and reduce read time, because of pay-as-you-go pricing models (paying hourly or yearly for usage to AWS). Consequently, AWS is getting so popular that many companies have switched from their own data centers to the public cloud.