A modern online game backend is not a single monolithic server.
It is a collection of specialized services working together to deliver real-time gameplay, persistent worlds, and social systems.

This chapter introduces the core architectural building blocks:

• Gateway / Connection Layer
• Room / Match Server
• World Server
• Matchmaking Service
• Persistence Layer (DB, Cache)
• Supporting Services (Chat, Social, Inventory, etc.)

By the end, you’ll understand how these pieces fit together into a working online game.