These are three main Cloud Computing Stack : Infrastructure as a Service, Platform as a Service and Software as a Service.
- SaaS applications are designed for end-users, accessible over the web.
- PaaS are set of tools and services to help developers design, develop, build & deploy application quickly.
- IaaS serves the need of storage, hardware, servers and networking components.
- any Service on-demand.
- any Platform on-demand.
- large Infrastructure on-demand.
Elasticity of cloud computing brings scalability & accessibility to the applications.
Examples : Amazon AWS (EC2), Google Cloud (Gmail), Microsoft Azure(Sky Drive) etc.