Scaling Systems — Handling Millions of Users

### What is Scalability?

Scalability means the system’s ability to handle increased traffic without performance degradation. Scalability measures the application's ability to withstand increased load without sacrificing performance or crashing.

### What is Latency?

Latency means the time taken to respond to a user request. It is measured as the duration between a User Action and the System Response.

### Types of Latency

**Network Latency** The time taken for data to travel from Point A to Point B. *Solution:* Use a Content Delivery Network (CDN) and place servers physically closer to users.

**Application Latency** The time taken by the application code to process the request. *Solution:* Conduct load testing, profile the code, and identify bottlenecks (e.g., slow database queries).

### Why Low Latency Matters

Low latency is absolutely critical in domains like Trading Platforms and Multiplayer Games. A delay directly impacts user trust and destroys the user experience.