ANSWER

• Infrastructure-as-a-service (IaaS) – vendors provide the physical data centers and network hardware.  Typically clients will pay based only on the amount of resources they use.  

• Platform-as-a-service (PaaS) – a delivery model in which the consumer creates the software using the tools, libraries, and preconstructed services from the provider while maintaining control over the configuration and deployment of the software.

• Software-as-a-service (SaaS) – a software delivery model in which the software, and usually the data, is provided by the vendor and hosted “in the cloud”.  Vendors run the software application for you. The software can be seamlessly and continually updated.

• Reduced Set Up Costs - Cloud computing minimizes large upfront investment in hardware and software. Additionally, it decreases the need for IT staff to maintain the hardware and software.  Some staff are often still needed but on a dramatically smaller scale.  Cloud computing distributes the cost of expensive hardware and software across many smaller companies.

• Scalability - Cloud services are readily scalable to meet the needs of the client with clients paying for resources as they are needed (usually following a tiered pricing structure).  With auto- scaling (elastic) services, clients can often receive real-time scaling with no additional action necessary.

• Lower Barriers to Entry - Cloud computing gives small and mid-size businesses access to the types of infrastructure and sophisticated technology that previously would have required the deep pockets of a big corporation.   

• Limited Need for Expertise - Cloud computing in most cases limits the need to hire technology or security experts.  Given the relatively new nature of Infrastructure as a Service, some expertise is still warranted to ensure that servers and nodes stay up and running, but certainly less than what would have previously be needed.  As you move towards Software as a Service almost no expertise is required.

• Collaboration - Cloud computing offers software and services that can be accessed by any computer, anywhere, anytime. This improves the collaboration that can be achieved by distributed teams and organizations in a global workforce.

• Lack of Availability - Cloud service and infrastructure can still go down.  If it does, your organization can be left without important information or software for hours.

• Data Ownership and Exchange - If your organization stops using a cloud software or service, can you retrieve all of the data that you have accumulated over time?  Additionally, can you be sure that the provider of the software or service has properly disposed of your data?

• Privacy and Control - What is the service provider doing with your data? Are they protecting the data or are they collecting it and using it for other purposes for their gain?