How do you architect systems to handle change and evolve over time?

When architecting systems that must evolve, I focus on modularity, loose coupling, and clear versioning. I start by decomposing the system into microservices or bounded contexts, each with its own database and API contract. I use an API gateway to centralize routing and enforce authentication. For data, I adopt a schema registry and versioned APIs so that new fields can be added without breaking clients. Infrastructure is defined as code (Terraform, CloudFormation) and deployed via CI/CD pipelines, allowing rapid iteration. Feature flags enable gradual rollouts. I also design for observability—metrics, logs, and tracing—to detect regressions early. In a recent SaaS product, this approach let us add new features every two weeks without downtime, and we could roll back a problematic release in minutes.