The largest segment of cloud computing is Software as a Service (SaaS). This segment currently generates more than half of the total cloud computing market's revenue and has become a common delivery model for many enterprise applications. Popular applications of SaaS include customer relationship management and enterprise resource planning software. Under this model, customers pay for access to software and databases, while the infrastructure and platforms are managed by the service provider. Salesforce, Microsoft, Adobe, and SAP are all major players in this segment.
On the next tier, Platform as a Service (PaaS) grants customers access to a computing platform for application development. This platform may include an operating system, web servers, databases, and the access to one or more programming-language environments. Salesforce has the highest market share in the PaaS segment, although other established players like Amazon and Microsoft also hold sizeable portions. While experts predict the cloud platform market will grow rapidly over the next decade, it is nevertheless expected to remain the smallest cloud computing segment by some margin.
Finally, Infrastructure as a Service (IaaS) gives customers access to off-site support in the form of storage, servers, virtual machines, and networking. At present, it is less than half the size of the SaaS market; however, research shows that traditional IT infrastructure spending is beginning to stagnate while more and more companies adopt cloud IT infrastructure solutions. The leading provider, Amazon, controls almost a third of the market, a share equal to the next two providers, Microsoft and IBM, combined.