> For the complete documentation index, see [llms.txt](https://docs.coherence.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coherence.io/0.4.14/resources/glossary.md).

# Glossary

### Archetype

Group of Components that define a type. Makes use of LODs.

### Client

Allows a User to interact with the World. Connects to Replication Server.

### Command

Allows for sending an instruction to an Entity that may be running on a different machine.

### Component

Part of ECS. Describes a characteristic or aspect of an Entity.

### ECS

Stands for Entity Component System. An entity system where entities are made of components.

### Entity

An instance of an Archetype. Part of ECS.

### Event

Allows for signalling that something of significance has occurred allowing interested listeners to act on it.

### Live Query

Allows the Client to specify a subset of the World to receive updates from. Acts as a filter to exclude updates on less relevant entities that could otherwise result in undesired latency.

### LOD

A partial representation of an Archetype. Allows for specifying priorities of components within an Archetype.

### Protocol Code Generator

Generates the client schema source file (e.g. schema.cs) that automatically handles serialization/deserialization of an ECS world, commands, and events.

### Replication Server

Replicates the state of the world to the connected Clients and Simulators.

### Simulator

Responsible for simulating a subset of the game world. Connects to Replication Server through which the state gets replicated to Clients.