Cloud services can be provided at different levels like at the level of platforms, applications or infrastructure. There are many Cloud services that are currently available to the public and few of them are as follows
Software-as-a-Service refers to the applications delivered through a web-rich client or any web browser to the end user. It is the largest cloud market that is growing very quickly. Few of the applications of SaaS require plugins and the rest can be run directly from a web browser without any installations or downloads required. SaaS makes it quite easy for the ventures to streamline support and maintenance and eliminates the need to install and run applications on single computers. The rest can be handled by the vendors like runtime, data, applications, virtualization, middleware, networking, storage, servers, and OSes. some popular types that SaaS offers are customer relationship management, healthcare-related applications and email and collaboration. Both large and small enterprises are implementing SaaS as their additional source of revenue to have a competitive edge over others. Examples of SaaS include DropBox, CloudNumbers and Microsoft OfficeLive.
Platform-as-a-Service provides more room for customization like for a programmer to acquire a bespoke platform (such as software, libraries, and operating system) or a framework that is mainly used to carry out a specified task such as develop or customize applications. With this technology testing, development and deployment of applications get simple, quick and cost-effective. PaaS enables a third-party provider or enterprise operations to manage servers, networking, storage, OSes and virtualization itself. Applications using PaaS inherit cloud attributes such as SaaS enablement, high-availability, scalability, multi-tenancy, and more. As PaaS automates business policy, helps migrate apps to hybrid model and reduces the amount of coding necessary, businesses benefit a lot from it. Examples of PaaS include VMforce, SalesForce, Google AppEngine and Joyent Accelerator.
Infrastructure as a Service (IaaS) which is a cloud infrastructure service is a self-service model for monitoring, assessing and managing infrastructures, such as networking, storage, networking services (firewalls) and compute (bare metal or virtualized). Unlike SaaS and PaaS users, IaaS users are responsible for managing runtime, data, middleware, applications, and OSes. IaaS helps users gain infrastructure later on top of which they can install the required platform. It provides maximum control of a computer infrastructure. Examples include IBM Cloudburst, Eucalyptus Community Cloud, and Amazon EC2.