What is Cloud Computing?

As the beginner, The first question comes in mind is "What is cloud computing?", "How it works?", "Any example from real life?". Before proceeding Salesforce terminologies, it is always required to understand the cloud computing technology as Salesforce is completely based on Cloud! Below I have posted the basic functional overview about cloud that will require you to proceed with further Salesforce knowledge.

What is Cloud Computing?

In simplest words, Cloud computation is the storing and accessing the files, data, application over internet that are actually not hosted on your system.

We all save files, data into the hard disk drive. Install softwares locally and access them. This the same concept in virtual manner. Suppose you and your friends are connected to single CPU. storing data to single cpu. Here in this case, both have data stored into single place. This is what exactly done in cloud computing concept but in more secure and reliable way.

With cloud computing technology you have followinf feasibility:

• No need to maintain heavy softwares, hardwares.
• Running 24 by 7.
• Easy integration with other systems like EBS.
• No software rather than browser required to use service.

Characteristics of Cloud Computing

• On-demand: Resources are always available whenever you want.
• Scalable: Increase/Decrease resources as per your need.
• Multi-tenant: The resources are generally shared with multiple users. But the data is secured so that no one can access it.
• Reliability: Maximum uptime so that users can access service any time.

Cloud computing Types

• A public cloud is one based on the standard cloud computing model, in which a service provider makes resources, such as applications and storage, available to the general public over the Internet. Public cloud services may be free or offered on a pay-per-usage model. Example: Box.com, Dropbox.com.
• A private cloud is designed to offer the same features and benefits of public cloud systems, but removes a number of objections to the cloud computing model including control over enterprise and customer data, worries about security, and issues connected to regulatory compliance.
• A hybrid cloud is a composition of at least one private cloud and at least one public cloud. A hybrid cloud is typically offered in one of two ways: a vendor has a private cloud and forms a partnership with a public cloud provider, or a public cloud provider forms a partnership with a vendor that provides private cloud platforms.

Service models in cloud computing

• Infrastructure as a Service (IaaS) means you're buying access to raw computing hardware over the Net, such as servers or storage. Since you buy what you need and pay-as-you-go, this is often referred to as utility computing. Ordinary web hosting is a simple example of IaaS: you pay a monthly subscription or a per-megabyte/gigabyte fee to have a hosting company serve up files for your website from their servers.
• Software as a Service (SaaS) means you use a complete application running on someone else's system. Web-based email and Google Documents are perhaps the best-known examples. Zoho is another well-known SaaS provider offering a variety of office applications online.
• Platform as a Service (PaaS) means you develop applications using Web-based tools so they run on systems software and hardware provided by another company. So, for example, you might develop your own ecommerce website but have the whole thing, including the shopping cart, checkout, and payment mechanism running on a merchant's server. Force.com (from salesforce.com) and the Google App Engine are examples of PaaS.
• Network-as-a-Service (NaaS) is a business model for delivering network services over the Internet on a pay-per-use or subscription basis.

Pros & Cons

Pros 

• Lower upfront costs and reduced infrastructure costs.
• Easy to grow your applications.
• Scale up or down at short notice.
• Only pay for what you use.
• Everything managed under service level agreement (SLAs).
• Overall environmental benefit.

Cons

• Higher ongoing operating costs. Could cloud systems work out more expensive?
• Greater dependency on service providers. Can you get problems resolved quickly, even with SLAs?
• Risk of being locked into proprietary or vendor-recommended systems? How easily can you migrate to another system or service provider if you need to?
• What happens if your supplier suddenly decides to stop supporting a product or system you've come to depend on?
• Potential privacy and security risks of putting valuable data on someone else's system in an unknown location?
• If lots of people migrate to the cloud, where they're no longer free to develop neat and whizzy new things, what does that imply for the future development of the Internet?
• Dependency on a reliable Internet connection.