1. Origin and the NIST definition #
NIST (National Institute of Standards and Technology) established an authoritative industry definition to clarify what cloud computing really is.
A paradigm shift #
Cloud computing is not just a technological evolution; it is a change of business model. You move from owning IT (buying servers) to consuming IT (renting a service). According to NIST, the cloud must provide ubiquitous, convenient, on-demand network access to a shared pool of configurable resources.
2. The 5 essential characteristics #
- On-demand self-service: you deploy your instances without any human intervention from the provider.
- Broad network access: your services are accessible everywhere through standard protocols (HTTP/HTTPS).
- Resource pooling: the physical infrastructure is shared between several customers (multi-tenancy) in an isolated, secure way.
- Rapid elasticity: capacity adapts automatically to the workload.
- Measured service: every resource consumed is tracked, enabling billing based on exact usage.
3. Benefits for the business #
Adopting the cloud offers three major pillars: agility (test an idea in minutes), scalability (support millions of users without changing the code) and innovation (access advanced AI or big data services without prior infrastructure expertise).
Hands-on: cloud resources from the command line #
Seeing self-service and measurement at work.
The 5 characteristics in one picture #
Self-service provisioning #
# AWS : une machine virtuelle en une commande
aws ec2 run-instances --image-id ami-0abcdef1234567890 --instance-type t3.micro --count 1 --key-name ma-cle
# Azure
az vm create -g demo -n vm1 --image Ubuntu2204 --size Standard_B1s --generate-ssh-keys
# Google Cloud
gcloud compute instances create vm1 --machine-type=e2-micro --image-family=debian-12 --image-project=debian-cloud
# Mesurer ce que l'on consomme (service mesuré)
aws ce get-cost-and-usage --time-period Start=2026-10-01,End=2026-10-18 --granularity=DAILY --metrics UnblendedCostCommon mistake: Resources created through self-service keep being billed as long as they exist: delete them after a lab (aws ec2 terminate-instances,az group delete).
