Introduction to System Design Interviews

Welcome to the System Design Learning Center. This guide will help you master system design interviews through a structured, practical approach.

How This Course Works

Rather than memorizing solutions to specific problems, you'll develop the judgment to design systems you've never seen before. We've organized the material into four sections that build on each other:

1. Interview Framework

Before diving into technical concepts, you need a repeatable process for tackling any system design question. The Interview Framework teaches you how to:

• Structure your 45-minute interview from start to finish
• Ask the right clarifying questions
• Scope the problem appropriately
• Present your design clearly and handle follow-ups

This framework is your foundation. Every practice problem and real interview will follow this structure.

2. Key Concepts

System design interviews test your understanding of fundamental concepts that apply across all distributed systems. The Key Concepts section covers:

• Non-Functional Requirements — Scalability, availability, consistency, latency, and other qualities that define system behavior
• Network Communication — HTTP, WebSockets, RPC, and how services talk to each other
• Data Modeling — Designing schemas, choosing between SQL and NoSQL, and understanding data access patterns
• API Design — REST, GraphQL, and designing clean interfaces between components
• Consistent Hashing — How to distribute data across nodes and handle scaling
• Numbers to Know — Latency figures, storage estimates, and back-of-envelope calculations

These concepts will come up in every system design discussion. Know them cold.

3. Building Blocks

Every large-scale system is assembled from a common set of components. The Building Blocks section teaches you when and how to use:

• Databases — Relational vs NoSQL, replication, sharding, and choosing the right storage
• Blob Stores — Storing and serving large files like images and videos
• Load Balancers — Distributing traffic across servers
• CDNs — Caching content close to users for faster delivery
• Distributed Caches — Speeding up reads and reducing database load
• Message Queues — Decoupling services and handling asynchronous work
• Pub/Sub Systems — Broadcasting events to multiple subscribers
• Rate Limiters — Protecting services from overload

Think of these as your toolkit. In any design interview, you'll combine these building blocks to solve the problem at hand.

4. Practice Questions

Finally, the Questions section puts everything together with real interview problems. Each question walks through a complete solution using the interview framework, showing how to apply the concepts and building blocks you've learned.

Recommended Learning Path

If you're new to system design, go through the sections in order. Start with the Interview Framework, then build your knowledge with Key Concepts and Building Blocks, and finally practice with the Questions.

If you have some experience, you might skim the Key Concepts as a refresher, spend more time on Building Blocks you're less familiar with, and jump into practice questions sooner.

If you're short on time, at minimum read the Interview Framework and work through two or three practice questions. The framework alone will significantly improve how you structure your answers.

What You'll Be Able to Do

After completing this course, you'll be able to:

• Walk into a system design interview with a clear, repeatable process
• Break down ambiguous problems into concrete technical decisions
• Select appropriate technologies for different requirements
• Estimate capacity needs and identify bottlenecks
• Explain your reasoning clearly, including the trade-offs you considered

Let's get started. Click "Next" to learn the Interview Framework.