How should I learn low-level and high-level system design?

For LLD, begin with OOP fundamentals, clean code, SOLID principles, and a small set of common design patterns. Practice implementing them rather than memorizing definitions. For HLD, learn how services, databases, caches, queues, and load balancers fit together, then study bottlenecks, replication, partitioning, sharding, and failure handling.

Books such as *Designing Data-Intensive Applications* and *System Design Interview* by Alex Xu are useful. When practicing, draw the design and explain why you chose each component, including the trade-offs. Interview preparation should focus as much on communicating decisions as on naming technologies.

Don’t overcomplicate the order. Pick a project or problem, choose a reasonable architecture, build it, and iterate. You’ll naturally encounter topics such as APIs, data modeling, caching, queues, and scaling as the project grows. Repeating that process is more valuable than trying to master every topic before starting.

The main way to improve is to design and build things repeatedly. Start with a manageable project, make your assumptions explicit, draw the architecture, implement part of it, then revisit the design after seeing its weaknesses. Studying existing systems helps, but practice is what turns the concepts into instinct.

A good progression is to practice LLD with smaller components—such as a parking lot, notification service, or elevator controller—then move to HLD exercises like a URL shortener, file storage service, or messaging platform. For every exercise, clarify requirements first, estimate scale, define APIs and data models, sketch the main components, and identify bottlenecks and failure cases.

Afterward, compare your design with a reference solution, but don’t copy it blindly. The important skill is being able to explain what you would change if traffic, consistency requirements, latency, or availability targets changed.