The term Cloud refers to a Network or the Internet. In other words, we can say that Cloud is something, which is present at a remote location. Cloud can provide services over a network, i.e., on public networks or on private networks, i.e., WAN, LAN or VPN. Applications such as e-mail, web conferencing, customer relationship management (CRM), all run in the cloud.

Manipulating, configuring and accessing the applications online is referred to as Cloud Computing. In this architecture, there is no need for us to install software on our local PC. We can overcome the platform dependency issue through cloud computing. It makes our business application mobile and collaborative.

Infrastructure As A Service (IAAS) IaaS provides access to fundamental resources such as physical machines, virtual machines, virtual storage, etc. Platform As A Service (PAAS) PaaS provides the runtime environment for applications, development & deployment tools, etc. Software As A Service (SAAS) SaaS model allows to use software applications as a service to end users.

There are many other service models all of which can take the form like XaaS, i.e., anything as a Service. This can be Network as a Service, Business as a Service, Identity as a Service, Database as a Service or Strategy as a Service. The Infrastructure as a Service (IaaS) is the most basic level of service.

Virtualization is a technique, which allows to share single physical instance of an application or resource among multiple organizations or tenants (customers). It does so by assigning a logical name to a physical resource and providing a pointer to that physical resource when demanded. The Multitenant architecture offers virtual isolation among the multiple tenants and therefore the organizations can use and customize the application as though they each have its own instance running.

Service-Oriented Architecture helps to use applications as a service for other applications regardless the type of vendor, product or technology. Therefore, it is possible to exchange of data between applications of different vendors without additional programming or making changes to services.