What is Cloud Computing?
Learn what cloud computing is, how on-demand and pay-as-you-go models work, key benefits over owned hardware, and how to explain it in an AWS interview.
Expected Interview Answer
Cloud computing is the on-demand delivery of computing resources — servers, storage, databases, networking, and software — over the internet, billed on a pay-as-you-go basis instead of being bought and run on owned hardware.
Instead of provisioning physical servers in a data center you control, you request virtualized capacity from a provider like AWS through an API or console, and it is provisioned in minutes. The provider owns and maintains the underlying hardware, power, cooling, and networking, while you consume resources as metered services. This shifts capital expenditure on infrastructure into operational expenditure that scales with usage, and it lets capacity grow or shrink automatically as demand changes. Core traits are on-demand self-service, broad network access, resource pooling across tenants, rapid elasticity, and measured billing.
- No upfront hardware capital expenditure
- Elastic scaling up or down with demand
- Pay only for resources actually consumed
- Global reach without building physical data centers
- Provider handles hardware maintenance and failures
AI Mentor Explanation
Cloud computing is like renting a fully equipped stadium and ground staff for a single tournament instead of building and maintaining your own cricket ground year-round. You pay only for the days you use the pitch, floodlights, and seating, and the venue owner scales seating capacity up for a final and back down afterward without you ever touching the groundskeeping.
Step-by-Step Explanation
Step 1
Request resources on demand
You provision compute, storage, or database capacity via an API or console instead of ordering physical hardware.
Step 2
Provider abstracts the hardware
AWS owns and operates the physical servers, racks, power, and cooling behind the scenes.
Step 3
Resources are pooled and virtualized
Multiple tenants share the same physical infrastructure safely through virtualization and isolation.
Step 4
Capacity scales elastically
Resources automatically or manually expand and contract to match real-time demand.
Step 5
Usage is metered and billed
You are charged for what you actually consume, whether by the second, GB, or request.
What Interviewer Expects
- Defines cloud computing as on-demand, metered access to shared computing resources
- Distinguishes it from owning and maintaining physical hardware
- Mentions elasticity and pay-as-you-go pricing
- Can name core resource types: compute, storage, database, networking
- Understands the provider handles hardware maintenance and availability
Common Mistakes
- Describing cloud computing as just 'someone else's computer' without mentioning elasticity or metering
- Confusing cloud computing with a specific service like storage alone
- Assuming cloud always means public internet-facing, ignoring private and hybrid models
- Forgetting that billing is usage-based rather than flat-rate ownership
Best Answer (HR Friendly)
“Cloud computing means renting computing power, storage, and other IT resources over the internet instead of buying and running your own servers. Companies pay only for what they use, and can scale up or down quickly, which saves money and speeds up how fast new products get built.”
Code Example
# Launch a virtual server (compute) on demand
aws ec2 run-instances \
--image-id ami-0abcdef1234567890 \
--instance-type t3.micro \
--count 1
# Output (truncated)
# {
# "Instances": [
# { "InstanceId": "i-0123456789abcdef0", "State": { "Name": "pending" } }
# ]
# }
# Terminate it when no longer needed -- billing stops
aws ec2 terminate-instances --instance-ids i-0123456789abcdef0Follow-up Questions
- What are the main service models: IaaS, PaaS, and SaaS?
- What is the difference between public, private, and hybrid cloud?
- How does elasticity differ from scalability?
- What is the shared responsibility model in cloud computing?
- What cost risks come with pay-as-you-go pricing if left unmanaged?
MCQ Practice
1. Which characteristic best distinguishes cloud computing from traditional on-premises infrastructure?
The defining trait of cloud computing is on-demand provisioning with usage-based billing, unlike owning fixed physical hardware.
2. Who is responsible for maintaining the physical servers and data centers in a public cloud model?
In public cloud, the provider owns and maintains the underlying physical infrastructure, while customers consume virtualized resources.
3. What does 'elasticity' mean in the context of cloud computing?
Elasticity is the ability of cloud capacity to scale up or down automatically or on request as workload demand changes.
Flash Cards
What is cloud computing? — On-demand delivery of computing resources over the internet with usage-based billing instead of owned hardware.
What is the pay-as-you-go model? — Billing based on metered consumption of resources rather than a fixed upfront purchase.
What does elasticity mean in cloud terms? — Automatic or on-demand scaling of resource capacity to match real-time workload demand.
Who maintains the physical hardware in public cloud? — The cloud provider (e.g., AWS) owns, operates, and maintains the underlying data centers and hardware.