Scalability is the ability of a system to keep working well when the number of users, data, or workload grows.
It comes from the world of software, but it also applies to infrastructure, databases, and even business models. If an app runs great with 100 users but crashes when it hits 1,000, it’s not scalable. On the other hand, if it can grow without a noticeable drop in performance (or with minimal changes), then it has good scalability.
You can scale vertically (upgrade the machine: more memory, better processor) or horizontally (add more machines and split the work). Picture a pizzeria: vertical scaling means buying a bigger oven; horizontal scaling means opening another branch. In the cloud (like with AWS, Google Cloud, or Azure), horizontal scaling is usually easier and cheaper in the long run.
Why is scalability so important?
Because in tech, anything can blow up overnight. A startup can jump from 10 users to 10,000 in just a few weeks. If your system can’t handle that, you lose people. A scalable system is designed to add resources (like servers or network capacity) without needing to start from scratch.
It’s like having a hot dog cart that turns into a gourmet grill without burning down the kitchen.
Want to see it from a technical angle? Here’s a solid AWS guide.
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