What is Cloud computing?
Cloud computing  is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.
How this came from
Cloud Computing comes into focus only when we think about what IT always needs: a way to increase the capacity or add capabilities on the fly without investing in the new infrastructure, training new personnel, or licensing new software.
Therefore such offering encompasses any subscription-based or pay-per-use service that, in real time over the internet, extends IT's existing capabilities.
What is Oracle Cloud?
The Oracle Cloud is an enterprise cloud for business.
This offers self-service business applications delivered on an integrated development and deployment platform with tools to rapidly extend and create new services.
With predictable subscription pricing, our cloud delivers instant value and productivity for end users, administrators and developers.
Oracle perceives the following as the key business benefits from Cloud Computing:
- Reduced CAPEX and OPEX
- Improved agility
- Faster time to market
What is unique about Oracle Cloud?
Oracle Cloud delivers a broad set of industry-standards based, integrated services that provide customers with subscription-based access to Oracle Platform Services, Application Services, and Social Services, all completely managed, hosted and supported by Oracle.
Offering a wide range of business applications and platform services, the Oracle Cloud is the only cloud to enable customers to avoid the data and business process fragmentation that occurs when using multiple, siloed public clouds.
Oracle Cloud is powered by leading enterprise-grade infrastructure, including Oracle Exadata and Oracle Exalogic, providing customers and partners with a high-performance, reliable, and secure infrastructure for running critical business applications.
Oracle Cloud enables easy self-service for both business users and developers. Business users can order, configure, extend, and monitor their applications. Developers and administrators can easily develop, deploy, monitor and manage their applications.
What are characteristics or different model exist?
This cloud model promotes availability and is composed of five essential characteristics, three service models, and four deployment models.
Five Essential Characteristics
- On-demand self service -Users are able to provision, monitor and manage computing resources as needed without the help of human administrators
- Broad network access - Computing services are delivered over standard networks and heterogeneous devices
- Rapid elasticity - IT resources are able to scale out and in quickly and on an as needed basis
- Resource pooling - IT resources are shared across multiple applications and tenants in a non-dedicated manner
- Measured service - IT resource utilization is tracked for each application and tenant, typically for public cloud billing or private cloud chargeback
Key service models of Oracle Cloud Computing are as follows:
Customers are adopting cloud computing in many different ways.
- Software as a Service (SaaS) - In this model applications delivered as a service to the end-users typically through a Web browser (for example, webmail). Oracle CRM-on-Demand is such an example untill date for such offering from Oracle.
- Platform as a Service (PaaS) - In this model an application development and deployment platform delivered as a service to developers who use the platform to build, deploy and manage the SaaS applications.
- Infrastructure as a Service (IaaS) - In this model ,Compute servers, storage and networking hardware delivered as a service.
In order to get more insights, Figure1 below shows the diagram for Oracle products avaiable in PaaS
The platform as a service typically includes databases, middleware and development tools, mostly avaiable as a service through the internet.
Oracle offers a comprehensive PaaS product offering for public cloud service providers and enterprise customers to build their own public clouds. The Oracle calls this as Oracle PaaS Platform.
The Oracle PaaS Platform is based on Oracle grid technologies including Oracle Database with Real Application Clusters and Oracle application grid including WebLogic Server, Coherence in-memory data grid and the JRockit JVM. On top of this foundation of clustered middleware and database technologies, the Oracle PaaS Platform also includes components such as Oracle SOA Suite, Oracle BPM Suite, Oracle Identity Management and Oracle WebCenter.
What are different deployment models of Oracle Cloud Computing?
The following are the three key deployment models of Oracle Cloud Computing:
- Private Clouds - For exclusive use by a single organization and typically controlled, managed and hosted in private data centers.
- Public Clouds - For use by multiple organizations (tenants) on a shared basis and hosted and managed by the third party service provider.
- Hybrid Clouds - When a single organization adopts both private and public clouds for a single application in order to take advantage of the benefits of both.
How best to use for Oracle Cloud?
Oracle Cloud can be leveraged for many different purposes. Customers can use Oracle Cloud to:
- Plan effectively and streamline their enterprise business processes
- Empower people and realize the power of their employees
- Boost sales, maximize revenues and engage customers
- Support customers and inspire great customer experiences
- Get social and collaborate seamlessly and securely
- Build and rapidly deploy applications
What services are available via Oracle Cloud?
Currently Oracle offerings many cloud services in three set of portfolio like Application, Platform, and Social.
Under Application Services
- ERP Services: A complete set of Financial Accounting, Project Management, Procurement, Sourcing, and Governance, Risk & Compliance solutions.
- HCM Services: This includes complete Human Capital Management solution including Global HR, Workforce Lifecycle Management, Compensation, Benefits, Payroll and other solutions. Oracle Cloud starting at $9.50 per employee and month.
- Oracle Fusion Global Human Resources
- Oracle Fusion Benefits
- Oracle Fusion Global Payroll
- Oracle Fusion Goal Management
- Oracle Fusion Talent Management
- Oracle Fusion Talent Review
- Oracle Fusion HCM Analytics
- Oracle Fusion Workforce Compensation
- Oracle Fusion Performance Management
- Oracle Fusion Workforce Predictions
- Oracle Fusion Transactional Business Intelligence
- Talent Management Services: More or less this includes all five core module of five core modules ofOracle TBE Cloud Service:
- Performance Management
- Sales and Marketing Services: A complete Sales and Marketing solution including Sales Planning, Territory Management, Leads & Opportunity Management, and Forecasting.
- Customer Service and Support Services: A complete Customer Service solution including Web Self-Service, Contact Centers, Knowledge Management, Chat, and e-mail Management.
As part of Platform Services, Oracle offers a complete and comprehensive set cloud services that allow developers to build rich applications and business users to harness the platform. Specifically for developers, platform services will include:
- Database Services to manage data and build database applications
- Java Services to develop, deploy and manage Java EE applications
- Web Scripting Services to build Web applications rapidly
- Mobile Services to allow developers to build cross-platform native and HTML5 mobile applications for leading smartphones and tablets.
Documents Services to allow project teams to collaborate and share documents through online workspaces and portals.
Oracle Social Network is a secure private network that provides a broad range of social tools designed to capture and preserve information flowing between people, enterprise applications, and business processes.
Oracle Cloud Social Services provides the most broad and complete enterprise social platform available in the cloud today. Oracle's integrated social platform will include:
- Oracle Social Network to enable secure enterprise collaboration and purposeful social networking for business.
- Oracle Social Data Services to aggregate data from social networks and enterprise data sources to enrich business applications.
- Oracle Social Marketing and Engagement Services to enable marketers to centrally create, publish, moderate, manage, measure and report on their social marketing campaigns.
- Oracle Social Intelligence Services to enable marketers to analyze social media interactions and to enable customer service and sales teams to engage with customers and prospects effectively.
What is Oracle Cloud Customer Portal
The Oracle Cloud Customer Portal is a one-stop-shop for all your Oracle Cloud service lifecycle management needs. The portal is role-based and provides both business and operational details of the Oracle Cloud.
Not to confuse.
As with many widely hyped areas, there is much more variation within the broad spectrum of products referred to as “Cloud” that is immediately apparent.
- Private cloud products -This enable organizations to have complete control and visibility over security, compliance, and service levels, Oracle also helps organizations build, deploy, and manage their own cloud environments, including integrated application, platform, and infrastructure products and solutions.
Obtain more details from here Oracle’s private cloud offerings include
- Oracle Cloud Applications. A complete and modular set of enterprise applications, engineered from the ground up to be cloud-ready and to coexist seamlessly in mixed environments.
- Oracle Cloud Platform. A shared and elastically scalable platform for consolidation of existing applications and new application development and deployment.
- Oracle Cloud Infrastructure. A complete selection of servers, storage, networking fabric, virtualization software, operating systems, and management software to support diverse public and private cloud
- Managed cloud services. Oracle Managed Cloud Services delivers enterprise-grade, end-to-end managed cloud services across Oracle's portfolio of business applications, middleware, database, and hardware technologies. Organizations can deploy solutions according to their own specific needs and budget, and decide where applications are hosted. Obtain more details from here 
Welcome to Oracle Cloud! Oracle Cloud is avaiable via this link  . Your comment or input welcome.