Cloud computing is the delivery of computing resources — servers, storage, databases, networking, software, analytics, and intelligence — over the internet, on demand, with pay-as-you-go pricing. Instead of owning and operating physical hardware in your own data centers, you access technology services from a cloud provider only when you need them. This eliminates large upfront capital expenditures, replaces them with low variable costs, and lets organizations scale instantly in response to demand spikes. The three primary service models are Infrastructure as a Service (IaaS, e.g. virtual machines), Platform as a Service (PaaS, e.g. managed databases), and Software as a Service (SaaS, e.g. Gmail). When would you use cloud computing? Almost always — cloud is the default choice for new applications because of its pay-as-you-go pricing, global reach, managed services that reduce operational overhead, and the ability to scale from zero to millions of users without upfront hardware investment. The main exception is organizations with strict data sovereignty requirements or very predictable, high-utilization workloads where owning hardware can be cheaper (the 'buy vs. rent' crossover point). Common mistakes: treating the cloud as a simple lift-and-shift of on-premises architecture (you lose most of the cost and scalability benefits), underestimating egress costs for data-heavy workloads, and skipping cloud-native services (managed databases, queues, caches) in favor of self-managed equivalents that require more operational effort.
Example: Instead of buying expensive servers, Netflix uses cloud computing to stream videos to millions of people worldwide, scaling capacity up during peak viewing hours and reducing it overnight without purchasing additional hardware. Architecture use case: a startup launches on AWS with a single EC2 instance, then adds RDS for the database, S3 for file storage, CloudFront for CDN, and Auto Scaling groups — each addition coming from a managed service rather than custom infrastructure.
Category: cloud
Difficulty: basic