What is Cloud Computing?
“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.” –The National Institute of Technology (NIST)

Cloud Computing, often called “The Cloud”. Everyone uses it but, few know its inner workings.
Gartner, the famous consultancy calls it: “A style of computing where massively scalable IT related capabilities are provided “as a service” using Internet technologies to multiple external customers.”
As you will learn, Cloud Computing is clearly defined based on 5 key characteristics and 3 service delivery models.
What are characteristics of Cloud Computing?
According to the National Institute of Standards and Technology (NIST), there are 5 essential characteristics to The Cloud (1):
- On-demand self service – A consumer can unilaterally provision computing capabilities, like server time and network storage.
- Broad network access – This means access from anywhere with standard equipment like phones, tablets, laptops, and workstations.
- Resource pooling – Computing resources are pooled to serve multiple consumers using a multi-tenant model.
- Rapid elasticity – Capabilities can be provisioned to scale rapidly to any quantity at any time.
- Measured service – Cloud systems automatically control and optimize resource use by metering users.
In summation, you can access your pooled computing resources anytime from anywhere and you will pay per use (typically calculated based on data usage).
Traditional IT vs. How The Cloud Works Today
As mentioned above, there are various characteristics which give The Cloud its unique identity but then there’s the question of how does all this plumbing work.
Before that, let’s discuss how the old model worked.
Old IT Model = Christmas lights that broke when a bulb went out
In the old Traditional “break fix” IT model, there was little to no prevention of problems. They were simply repaired when a problem occurred.
And that’s not the worst of it, the fragile vertical structure of computers at the time made things very hard to change and manage.
When any moving part of these “Christmas lights” goes down, the whole thing goes down.
This means costly problems are rigidly embedded in the infrastructure itself due all the assets being tied together.
This created a far higher cost basis for managing ones IT infrastructure.
Thankfully we now have a better way of doing things.
“The Cloud” Is A Pay Per Use Utility Model
In 1961 at the MIT Centennial renowned computer science professor, John McCarthy, said: “If computers of the kind I have advocated become the computers of the future, then computing may someday be organized as a public utility just as the telephone system is a public utility.…The computer utility could become the basis of a new and important industry.”
What’s amazing is how right he was. (Think about all the streaming services we can’t live without like Netflix, Hulu, HBO+ etc.)
Today’s landscape of just Cloud steaming services alone sure looks very utility-like.
Hypervisors Allow You To Create a Virtual Computer within a Computer
It’s easy to miss some of the most significant cumulative components that make Technologies like Cloud Computing work.
One such Cloud enabling technologies is a Hypervisor which is a thin layer of code, firmware or hardware that facilitates the running of virtual machines.
This means that multiple operating systems can share a single hardware host. The hypervisor allows these virtual machines without disrupting the functionality of the core operating systems.

The 3 Cloud Service Models: Infrastructure, Platforms and Software
Cloud Computing has taken various forms in terms of how people use it and why. The various depends on the abstraction requirements of capabilities provided, meaning what functions need to be separated for independent operation.
The 3 main Cloud Service models are:
- IaaS: Infrastructure as a Service – Infrastructure as a service is where the IaaS provider is in charge of the data center equipment. The user is in responsible for managing the hardware and software.
- PaaS: Platform as a Service – Here the provider supplies a computing platform (including the operating system (OS), programming execution environment, database and web server). Users then build on this with no additional hardware or software.
- SaaS: Software as a Service – SaaS is the most common model where users access applications, software for a monthly or annual subscription fee.
Next, is a more detailed breakdown of various Cloud Computing delivery models and who manages them.
The 3 Cloud Computing Delivery Models: Private, Public and Hybrid
Regardless of the service model chosen (IaaS, PaaS, Saas etc.) there are three delivery models for users of The Cloud, private, public and hybrid.
There are varying reasons for using each which mainly consist of security, user access and cost.
Here are the 3 Cloud delivery models:
- Private Cloud – This operates solely for an organization internally or operated by a third party for the exclusive use of only that organization. This model is used in particular by industries with heavy regulations, security and compliance needs.
- Public Cloud – Computing resources and services are completely outsourced to a third party over an open network for public use. Any user with an internet connection can login to the network.
- Hybrid Cloud – A hybrid cloud is a combination of both Private and Public models. Most companies use some form of Hybrid Cloud because it isn’t always practical to have a Private Cloud for all data. The same goes for Public Cloud, which might not be the best choice for highly sensitive data.

Final Thoughts
Cloud Computing, it’s not rocket science but it is computer science.
After reading this you should have learned the 5 characteristics of The Cloud, The 3 main service and deployment models.
The 5 Cloud characteristics include: On-demand self service, Broad network access, Resource pooling, Rapid elasticity and Measured service.
The 3 main service models are: Infrastructure, Platform and Software-as-a-service (IaaS,Paas, and SaaS).
Finally, the 3 Cloud deployment models are: Public, Private and Hybrid.
Thanks for reading and May the Cloud be with you!
Easy to read, well illustrated.