## TL;DR
Multiplayer game networking delivers responsive real-time interaction over unreliable networks. The core challenges are latency compensation, state synchronization, and cheat prevention — solved through authoritative servers and client-side prediction.

## Core Architecture

### Authoritative Server Model
The server is the sole authority on game state. Clients send input commands; the server processes them and broadcasts results. This prevents client-side cheating (speed hacks, wallhacks) because the server validates every action.

### Client-Side Prediction
Players would experience unacceptable input lag (100-200ms) waiting for server confirmation. Instead, clients predict their own movement immediately and reconcile when the server's version arrives. Mispredictions cause rubber-banding — the visual snapback when correction occurs.

### Interpolation and Lag Compensation
Other players' positions are interpolated between the last two known states, displayed slightly behind real-time (typically 100ms). This creates smooth movement at the cost of slight delay. Lag compensation rewinds server state to the client's perceived time for hit detection.

### State Synchronization Strategies
- **Full state sync**: Send entire world state each tick (expensive, simple)
- **Delta compression**: Send only changed fields (efficient, complex)
- **Interest management**: Send only entities relevant to each player

## Transport Layer
UDP dominates game networking because:
- No head-of-line blocking (lost packets don't stall the stream)
- Application-level reliability control (resend only what matters)
- Lower latency than TCP (no connection handshake per packet)