Definition
Scalable systems are designed to handle increasing workloads or demand without compromising performance or availability. This is achieved by adding resources, such as more servers or processing power, either vertically by upgrading existing components or horizontally by adding more instances. Understanding scalability is crucial for building robust and cost effective solutions that can adapt to user growth and changing business needs. For instance, a popular e-commerce website scales its web servers during a holiday sale to manage the surge in customer traffic. This differs from systems that are simply available, as scalability implies the ability to grow capacity proactively. Concepts of scalability appear in domains like cloud computing and system architecture, relevant to certifications such as AWS Certified Solutions Architect.