What Is Cloud Computing ?

Cloud Computing is the use of Computing Resources(Hardware like Hypervisor,Storage,switches  & Software like Virtualization,vlan trafficing , dynamic ip allocation ) that are delivered as Service over the Network.It's called cloud since all these above mentioned resources can be scaled on request  and based on usage.

Why cloud Computing is preferred / benefits of Cloud Computing

• Scalability : -The customer doesn't have to know (and buy) the full capacity they might need at a peak time. Cloud computing makes it possible to scale the resources available to the application. A start-up business doesn't have to worry if the advertising campaign works a bit too well and jams the servers.
  
• Pay Per Use :- Customers pay only for what they use. They don’t have to buy servers or capacity for their maximum needs. Often, this is a cost savings.
  
• The cloud will automatically (or, in some services, with semi-manual operations) allocate and de-allocate CPU, storage, and network bandwidth on demand. When there are few users on a site, the cloud uses very little capacity to run the site, and vice versa.
  
• Reduces Cost :- Because the data centers that run the services are huge, and share resources among a large group of users, the infrastructure costs are lower (electricity, buildings, and so on). Thus, the costs that are passed on to the customer are smaller.
  
• Application programming interface (API):- Accessibility to software that enables machines to interact with cloud software in the same way that a traditional user interface (e.g., a computer desktop) facilitates interaction between humans and computers
  
• Virtualization technology allows servers and storage devices to be shared and utilization be increased. Applications can be easily migrated from one physical server to another.
  

Types of Cloud Computing :-

• Public Cloud
• Private Cloud
• Hybrid Cloud

Public Cloud  :- In public cloud applications, storage, and other resources are made available to the general public by a service provider. These services are free or offered on a pay-per-use model. Generally, public cloud service providers like Amazon AWS, Microsoft and Google own and operate the infrastructure and offer access only via Internet

Private Cloud : - Private cloud is cloud infrastructure operated solely for a single organization, whether managed internally or by a third-party and hosted internally or externally.

Hybrid Cloud : -  Hybrid cloud uses both public and private cloud infrastructure.

Cloud computing  Models

• Infrastructure as a Service (IaaS).  IaaS  offers  computers - physical or  virtual machines - and other resources like storage so that developers and IT organizations can use to deliver business solutions.Cloud providers typically bill IaaS services on a utility computing basis: cost reflects the amount of resources allocated and consumed.
  
• Platform as a Service (PaaS). Pass offers computing platform typically including operating system, programming language execution environment, database, and web server. Application developers can develop and run their software solutions on a cloud platform without the cost and complexity of buying and managing the underlying hardware and software layers.
  
• Software as a Service (SaaS). In the SaaS , the service provider hosts the software so you don’t need to install it, manage it, or buy hardware for it. All you have to do is connect and use it. SaaS Examples include customer relationship management as a service.