The Multiplayer High Level API

Unity’s multiplayer High Level API (HLAPI) is a system for building multiplayer capabilities for Unity games. It is built on top of the lower level transport real-time communication layer, and handles many of the common tasks that are required for multiplayer games. While the transport layer supports any kind of network topology, the HLAPI is a server authoritative system; although it allows one of the participants to be a client and the server at the same time, so no dedicated server process is required. Working in conjunction with the internet services, this allows multiplayer games to be played over the internet with little work from developers.

The HLAPI is a new set of networking commands built into Unity, within a new namespace: UnityEngine.NetworkingThe Unity system that enables multiplayer gaming across a computer network. More info
See in Glossary. It is focused on ease of use and iterative development and provides services useful for multiplayer games, such as:

• Message handlers
• General purpose high performance serialization
• Distributed object management
• State synchronization
• Network classes: Server, Client, Connection, etc

The HLAPI is built from a series of layers that add functionality:

This section of the manual explains how to use the multiplayer HLAPI.