Cloud Computing(I am specifically talking about public clouds) .People understand it ,use it but there remains some confusion between a traditional hosting on data center and cloud.
Rather a cloud is a collection of big blocks of data center.They do have real servers/storage/networks but what differs is how they leverage the end user to use it.It's public computing made possible.Like you go to a railway station and what matters to you is buy a ticket and board a train and should not be bothered about the large backbone of n/w in booking system or infrastructure of railways.
Similarly computing is being driven in public.you use some computing resources,pay for it for the duration of it and forget about it. Not like traditional data centers that you check about electricity regulations/power consumptions/failure/Air conditioning and then enter into some sort of written agreement with the owner of infrastructure.
When you are going to cloud,you don't even have to see or communicate with infrastructure owner.The Web has made it possible to sale infrastructure as service and thereafter software as service too.
They have published the per hour rate of computing resources as well as traffic usage.you have to just register with them ,chose your configuration and start an instance of machine from a already create image(you can deploy your own too).
you get a public DNS of the machine/public IP for the same and a control panel to manage it.you have all the control of firewall applicable to your resource.you can put your own rules and think if you ever have to see or meet a suited salesman from Data-center.
Web has made it possible.It's like banking,where most of they guy never visit physically to a branch to open/maintain a bank a/c.The service is all in public.
To conclude Cloud computing provides flexible, scalable, secure, and cost-effective IT infrastructure for businesses of all sizes around the world.Compute power, storage, and network bandwidth is available to you on-demand, you pay only for the resources you use……running on scalable, reliable, and secure infrastructure .