30 System Design Concepts Every Engineer Should Know (Without Losing Their Mind)
š§ Why You Should Care About System Design (Yes, Even You, Frontenders)
System design is the bridge between writing code and running successful software at scale. Whether you're building an MVP or designing systems that support millions of users, understanding core system design concepts can dramatically change how you build and think about software.
Below is a carefully crafted and in-depth list of 30 concepts you should know.
šļø The Basics ā Foundations You Canāt Skip
1. Client-Server Architecture
A design model where the client (usually a browser or mobile app) makes requests to a centralized server, which processes and returns responses. It's the foundation of how most web applications work.
2. IP Address
An IP address (Internet Protocol address) is a unique string of numbers assigned to each device connected to the internet. It allows devices to locate and communicate with each other over the network.
3. DNS (Domain Name System)
DNS converts human-readable domain names (like google.com) into machine-readable IP addresses. Without DNS, we'd have to remember IPs to access websites.
4. Proxy / Reverse Proxy
A proxy server acts as a gateway between clients and the internet. A reverse proxy does the oppositeāit takes requests from the internet and forwards them to backend servers. They're used for caching, load balancing, and security.
5. Latency
Latency is the delay before a transfer of data begins following an instruction. It affects how fast users perceive your application. Reducing latency improves user experience.
6. HTTP/HTTPS
HTTP (Hypertext Transfer Protocol) and its secure version HTTPS are protocols for transferring web pages on the internet. HTTPS uses encryption (via SSL/TLS) to secure data in transit.
7. APIs
APIs (Application Programming Interfaces) allow software systems to communicate with each other using defined rules. REST and GraphQL are two common API paradigms.
8. REST API
REST (Representational State Transfer) APIs use standard HTTP methods and are stateless. They follow conventions to structure URLs and handle requests with predictable outputs.
9. GraphQL
GraphQL is a query language for APIs that allows clients to request only the data they need. It's highly flexible and efficient compared to REST when dealing with complex or nested data.
10. Databases
Databases store structured or unstructured data. You can choose between relational (SQL) and non-relational (NoSQL) depending on data complexity and access patterns.
š Growth Stuff ā Scale Like a Pro
11. SQL vs NoSQL
SQL databases use structured schemas and support ACID transactions. NoSQL databases offer flexibility with unstructured data and are often used in high-volume, low-latency scenarios.
12. Vertical Scaling
Vertical scaling (scaling up) increases server capacity by adding more CPU, memory, or storage. It's simple but has physical limitations and a single point of failure.
13. Horizontal Scaling
Horizontal scaling (scaling out) adds more machines or nodes to distribute the load. It's more complex but allows handling increased traffic and redundancy.
14. Load Balancers
A load balancer distributes incoming network traffic across multiple servers to ensure no single server is overwhelmed. It improves availability and responsiveness.
15. Database Indexing
Indexes allow databases to find rows faster without scanning every row. They drastically improve query performance, especially on large datasets.
16. Replication
Replication copies data from one database server to others. It provides redundancy, improves read performance, and ensures availability in case of a server crash.
17. Sharding
Sharding splits large databases into smaller, faster, more manageable parts called shards. Each shard holds a portion of the data and can be stored on different servers.
18. Vertical Partitioning
Vertical partitioning divides a table into multiple tables based on columns. It helps reduce I/O by reading only the necessary columns for a query.
19. Caching
Caching stores frequently accessed data in memory or closer to the user. It reduces the load on backend systems and improves performance by minimizing redundant calculations or database queries.
20. Denormalization
Denormalization is the process of adding redundant data to improve read performance. It sacrifices write efficiency and storage for faster reads.
š§Ŗ Advanced Concepts ā Where Legends Are Born
21. CAP Theorem
CAP stands for Consistency, Availability, and Partition Tolerance. In a distributed system, it's impossible to guarantee all three simultaneously. Systems must choose trade-offs based on use case.
22. Blob Storage
Binary Large Object (Blob) storage is used for storing unstructured data like images, audio, or video. It is optimized for scalability and cost-efficiency.
23. CDN (Content Delivery Network)
A CDN stores cached versions of content in multiple geographical locations. It reduces latency by serving users from the nearest edge server.
24. WebSockets
WebSockets provide full-duplex communication channels over a single TCP connection. They're ideal for real-time applications like chat or collaborative tools.
25. Webhooks
Webhooks allow systems to notify each other of events via HTTP POST. They are commonly used for payment confirmations, CI/CD triggers, etc.
26. Microservices
Microservices is an architectural style where applications are composed of small, independent services. Each service focuses on a single business function and communicates via APIs.
27. Message Queues
Message queues enable asynchronous communication between services. Producers send messages to a queue, and consumers process them, improving decoupling and fault tolerance.
28. Rate Limiting
Rate limiting restricts the number of requests a client can make in a given time frame. It helps protect your APIs from abuse or overload.
29. API Gateways
An API Gateway acts as a single entry point for a set of microservices. It handles routing, authentication, monitoring, and load balancing.
30. Idempotency
Idempotent operations produce the same result no matter how many times they are executed. Ensuring idempotency is crucial for preventing duplicate transactions in APIs.
š Final Thoughts
System design is not just for interviewsāit's for building real-world, scalable, resilient software. Donāt try to learn everything in a day. Pick a few concepts, go deep, and apply them in projects.
Happy designing!