An Introduction to Cloud Technology

Cloud computing is renting computers, storage and software by the hour from someone whose entire business is keeping them running. You get an API and a console instead of a purchase order and a delivery van, and you pay for what you switch on. That is the whole idea. Everything else, the service names, the certifications, the diagrams with little clouds on them, is detail layered on top.

What the cloud actually is

The US National Institute of Standards and Technology published the definition everyone still quotes, Special Publication 800-145, back in 2011. It has aged well because it describes behaviour rather than products. NIST lists five essential characteristics: on-demand self-service, broad network access, resource pooling, rapid elasticity and measured service. If a supplier makes you raise a ticket and wait three days for a server, whatever they are selling is not cloud.

NIST also names four deployment models: private, community, public and hybrid. Most small and mid-sized businesses use public cloud for new systems and keep one or two older things on their own hardware, which is a hybrid estate whether anyone calls it that or not. Flexera’s 2026 State of the Cloud research found 73% of organisations operating hybrid, up three percentage points year on year, so the messy middle is the normal state, not a transitional phase.

The three service models in plain language

The three service models decide how much work stays with you. Infrastructure as a service hands you a virtual machine and a network, and you still patch the operating system. Platform as a service hands you a managed database or application runtime, and the provider patches underneath you. Software as a service hands you a finished application, and your job is configuration, data and user accounts.

That table is the single most useful thing to internalise, because it predicts where your effort goes and who is at fault when something breaks. We go deeper in our guide to the service models, including how each one is priced.

How the bill is put together

Cloud invoices have three main shapes: compute time, stored data, and data movement. The figures below were read from vendor price lists in October 2026 in their US regions, and they will drift, so treat them as orders of magnitude rather than quotes.

Notice what is missing: there is no line for the three days you spent sizing a server, the capital you tied up in hardware you half-use, or the weekend you lost to a failed RAID controller. Those costs are real, they just do not appear on an invoice, which is why like-for-like comparisons with on-premises kit are so often argued and so rarely settled.

Where cloud saves money, and where it quietly does not

Cloud wins clearly when demand is uneven, when you need to be in several countries, when the alternative is buying hardware you will outgrow, and when you would rather pay for a managed database than learn to tune one. It wins quietly on security patching, because managed services get patched whether or not anyone on your team remembers.

It loses when a workload is flat, predictable and already paid for. A steady database on owned hardware with three years left in it is not a cloud candidate on cost grounds alone. Flexera’s 2026 research estimated 29% of IaaS and PaaS spending is wasted, and reported that 71% of organisations now run a cloud centre of excellence to get that under control. The waste is not the provider’s fault. It is idle instances, oversized disks, forgotten test environments and data nobody deleted.

The practical conclusion is unglamorous. Cloud is cheaper than owning hardware only if somebody owns the bill. Set a monthly review, tag everything by project, and delete what nobody can explain. Our walkthrough of how to cut cloud costs without losing performance is the next thing to read if your invoice has been creeping.

What reliability you are really buying

Providers sell nines, but they sell them conditionally. Amazon’s Compute Service Level Agreement commits to a 99.99% Monthly Uptime Percentage at region level only when your instances run concurrently across two or more Availability Zones. A single instance gets 99.5%. Miss the target and you receive a service credit, starting at 10% of the bill, rising to 100% below 95.0% uptime. A credit is not compensation for lost trade.

Downtime is expensive enough to plan for properly. The Uptime Institute’s 2026 annual outage analysis reported that 57% of respondents said their most recent major outage cost more than $100,000, and for the second year running one in five put the cost above $1 million. Those are enterprise numbers, but the shape holds at smaller scale: the cost of being down for a day is almost always larger than the cost of the second Availability Zone you did not deploy.

A sensible first 30 days

You do not need a strategy document to start. You need one real workload, one budget alarm and a rule about who can create things.

1. Pick one workload that is annoying you. A file share people cannot reach from home, a staging site, a backup target. Not the finance system.
2. Open one account and turn on billing alerts first. Before any resource exists, set an alert at your intended monthly spend and another at double it.
3. Use managed services where you can. A managed database costs more per hour and less per year than a VM you patch yourself.
4. Tag everything with a project and an owner. Untagged resources are how 29% waste happens.
5. Decide your recovery targets before you build. How much data can you lose, how long can you be down? Write the numbers down and design to them.
6. Review the bill in month two, line by line. This is the single habit that separates teams who like their cloud from teams who resent it.

If you want a second pair of eyes on any of that, our cloud solutions work is delivered remotely for clients worldwide: assessment, build, migration and the monthly cost review. Clients who want hands-on-site support in Sri Lanka are looked after through eudora.lk. Two more posts worth reading before you commit: on-premises versus cloud for the money argument, and our provider comparison for the shortlist.

Thinking about a first move to cloud and want a plain assessment rather than a sales pitch? Tell us what you run today. Get in touch with Eudora Technology to talk about your project.