Cloud computing delivers IT resources over the internet with self-service, rapid elasticity, and measured usage. Understanding these traits helps you compare AWS to on-premises data centers.
Deployment models
- Public cloud — AWS, shared infrastructure, multi-tenant
- Private cloud — dedicated environment (can run on AWS Outposts or on-prem)
- Hybrid — mix of on-prem and cloud (common during migration)
Cloud benefits for developers
- No waiting weeks to procure hardware
- Experiment cheaply, then scale winners
- Managed databases reduce DBA toil for small teams
- Global CDN and edge services improve user latency
Relational data skills from SQL transfer directly to PostgreSQL on RDS.
CapEx vs OpEx mental model
On-prem: large upfront capital expenditure (CapEx) on servers. Cloud: ongoing operational expenditure (OpEx) aligned with usage—easier to start, requires cost monitoring.
Free tier / sandbox safety: Stay within free-tier limits, set billing alerts, and tear down resources you create for learning. Never paste real access keys, secret keys, or passwords into lessons, tickets, or chat.
Check your default region
aws configure get region
# Or inspect ~/.aws/config for [default] region = ...Always know which region you are in—resources do not automatically exist in every region.
Important interview questions and answers
- Q: What is elasticity?
A: Ability to add or remove capacity quickly—Auto Scaling groups exemplify this on EC2. - Q: Why monitor cloud costs?
A: Usage-based billing means forgotten resources (EIPs, NAT gateways, large EBS volumes) can surprise you.
Self-check
- What is the difference between CapEx and OpEx in cloud terms?
- Name two benefits of cloud for a small dev team.
Tip: Set a billing alarm on day one—even free-tier sandboxes can charge for NAT gateways and EIPs.
Interview prep
- Elasticity?
Ability to scale resources up or down quickly based on demand.
- OpEx vs CapEx?
Cloud shifts IT spend from upfront hardware CapEx to usage-based operational OpEx.