What is cloud computing? There is a de facto definition out there that NIST developed some time ago. NIST stands for National Institute of Standards and Technology.
Cloud Computing is the on-demand delivery of Information Technology (IT) resources over the Internet. On-demand pricing means that you only pay for what you use, similar to a pay-as-you-go plan with a mobile phone service company. The resources refer to storage of data, databases, and computing power. Organizations of all sizes are using cloud computing for a variety of reasons such as data backup, email, application software and game development, software testing, web applications for use by customers and employees, and big data analytics.
NIST says: “Cloud computing is a model for enabling ubiquitous, 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. This cloud model is composed of five essential characteristics, three service models, and four deployment models.”
The phrase “cloud computing” originates from the cloud symbol used by flow charts and diagrams to symbolize the Internet.
Essential Characteristics:
On-demand self-service. A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service provider.
Broad network access. Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, tablets, laptops, and workstations).
Resource pooling. The provider’s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacenter). Examples of resources include storage, processing, memory, and network bandwidth.
Rapid elasticity. Capabilities can be elastically provisioned and released, in some cases automatically, to scale rapidly outward and inward commensurate with demand. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be appropriated in any quantity at any time.
Measured service. Cloud systems automatically control and optimize resource use by leveraging a metering capability1 at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service.
Service Models:
Software as a Service (SaaS). In a word: Consume. The capability provided to the consumer is to use the provider’s applications running on a cloud infrastructure. The applications are accessible from various client devices through either a thin client interface, such as a web browser (e.g., web-based email), or a program interface. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.
Platform as a Service (PaaS). In a word: Build. The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages, libraries, services, and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage, but has control over the deployed applications and possibly configuration settings for the application-hosting environment. Microsoft’s PaaS and Saas is called Microsoft 365.
Infrastructure as a Service (IaaS). In a word: Host. The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, and deployed applications; and possibly limited control of select networking components (e.g., host firewalls).
Deployment Models:
Private cloud. The cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (e.g., business units). It may be owned, managed, and operated by the organization, a third party, or some combination of them, and it may exist on or off-premises.
Community cloud. The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off-premises.
Public cloud. The cloud infrastructure is provisioned for open use by the general public. It may be owned, managed, and operated by a business, academic, or government organization, or some combination of them. It exists on the premises of the cloud provider.
Hybrid cloud. The cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load-balancing between clouds).
YouTube Resources
Here is a simple introductory short 3-minute video called What is Cloud Computing?.
Here is another video that’s called Cloud Computing Services Models – IaaS PaaS SaaS Explained.
Here is a video for beginners that is longer (33 minutes). It’s called Cloud Computing Tutorial For Beginners | What is Cloud Computing | AWS Training | Edureka. Why Cloud? What is Cloud Computing is at 5:50. Cloud Models is at 6:45. Deployment Models is at 11:54. “Cloud Providers” is at 14:20. After this, there are several minutes of hands-on using AWS and MS Azure.
Here is a 13-minute video called Cloud Computing in the Year 2020.
There is a 24-minute introductory video on YouTube called Cloud Computing Tutorial for Beginners by Simplilearn.
Here is an older, longer video for beginners. It’s one hour and 16 minutes long and it’s called Introduction to Cloud Computing.