Lesson · 22 min

What Cloud Computing Actually Is

Understand what the cloud is, what changes when computing moves off your machine, and what it costs as well as what it saves.

By the end of this lesson you can

Define cloud computing and its essential characteristics
Explain what changes when computing moves off local hardware
Distinguish public, private, and hybrid cloud
Identify the genuine trade-offs of moving to the cloud

📘 Reading Lesson

Lesson Notes

Read through the key concepts before you try the challenge.

Somebody else's computers, rented by the hour

On the job

Lakeside Medical Associates is deciding where its systems should run.

The practice currently owns a server in a closet. It needs replacing, needs backups nobody has tested in a year, and stops the practice working entirely when it fails. A vendor proposes moving everything to the cloud. The manager wants to know what that actually means and what it would cost.

Your task: Understand cloud computing precisely enough to explain the trade-off, not just the sales pitch.

Cloud computing means using computing resources — servers, storage, applications — over the internet, provided and maintained by someone else, and paid for as you use them. The defining shift is from owning capacity to renting it.

Characteristic	Means
On-demand self-service	You provision resources yourself, without a purchase order
Broad network access	Reachable from any device with a connection
Resource pooling	Providers serve many customers from shared infrastructure
Rapid elasticity	Capacity scales up and down as demand changes
Measured service	You are billed for what you consume

The characteristics that define cloud computing

Consideration	On-premises	Cloud
Upfront cost	High — you buy the hardware	Low — you pay as you go
Ongoing cost	Lower, but plus maintenance and staff	Continuous subscription, forever
Maintenance	Yours: patching, backups, replacement	The provider's
Scaling	Buy more hardware and wait	Change a setting
Works without internet	Yes	Generally not
Physical control of data	Complete	Contractual rather than physical

Owning versus renting

The cloud is not automatically cheaper, and vendors rarely lead with that. It converts a large upfront purchase into a permanent operating cost, which is often the right trade for a small practice that cannot maintain a server properly — but over five years the total can exceed buying outright. Evaluate it on reliability, maintenance burden, and expertise you do not have, and treat any cost saving as something to verify rather than assume.

Model	Means	Suits
Public cloud	Shared infrastructure from a provider	Most small organizations
Private cloud	Infrastructure dedicated to one organization	Strict regulatory or control requirements
Hybrid cloud	A combination, with data moving between them	Keeping sensitive data in-house while using public capacity

Deployment models

Check your understanding

What is the most accurate description of the change a practice makes when it moves from an on-premises server to the cloud?

Challenge

Apply what you've learned in this lesson.

Evaluate a real decision rather than describing the concept.

List five cloud services you personally use. For each, note what it replaced.
For Lakeside's server replacement, list four arguments for moving to the cloud and four for buying a new server.
Estimate five-year costs both ways using real prices, stating your assumptions.
Write a one-paragraph recommendation naming the deciding factor. It should not be cost alone.

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