Now, to understand cloud we need to understand what we get from the vendors that offers cloud like Microsoft, IBM, Amazon etc. you are opening a data centre. And you need to…actually you don’t need to buy server, storage devices Few clicks and they will provide virtual machines, virtual storage, virtual infrastructure as per your requirement. Those server and storage exists somewhere, but you will access them online so it is virtual to you. those are virtual resource for u, infrastructure as a service But, here you are getting virtual machine like a new PC, you will be responsible all other aspect of deployment like OS, software, user interface etc Google app engine, Microsoft azure, Amazon AWS, Engine yard these are well known PaaS i.e. platform as a service. you will be provided with many preconfigured components which are maintained by the service provider, including their programming language, application server and database. Say, You are using Google app engine, you will get development framework to develop program in Java, Python or Go. U will be able to use Google infrastructure to build, store and run your app, so that it is available to others 24 x 7 you are getting a whole platform which offers virtual infrastructure, tool, assistance to for app development. It is platform as a service you get a software to do your work online and save it and log out.
That is software as service. Everything down below the application to the infrastructure is vendor’s headache. log in, do your work and log out Most popular type here is software for customer relationship management. Data centers pay a minimum fee as subscription and their employees log in and use the software online and log out. No need to buy it for lifetime for single PC. Most of those software provided through thin client interface like a web browser. So, you can log in from any PC as long as you have internet access. I will try to be simple and precise Cloud computing refers to applications and services that run on a distributed network using virtualized resources and accessed over internet