# Pak Loading

Check here to learn how REPak works and how to build a rpak.

### Pak Types and Load Paths

**RPAK** loading behavior depends on the server type:

* Client / Listen Server
  * Loads `.rpak` files from the `paks/Win64` folder.
  * These files must include **all dependencies** required for loading.
  * If any `.starpak` files are associated, they **must** also be included.
* Dedicated Server
  * Loads `.rpak` files from the `paks/Win64_Server` folder.
  * Server only `.rpak` files should exclude unnecessary assets such as textures, materials, and UI assets.
    * Avoid using client rpaks on dedicated servers. Doing so will increase memory usage and slow down load times.
  * `.starpak` files are **not required** for dedicated server.

### Loading RPAK Files

The SDK supports two methods for loading `.rpak` files:

* Preloaded Rpaks
  * These `.rpak` files are loaded during the first map load and **remain loaded for the entire session**.
  * To designate `.rpak` files as preloaded, a `preload.rson` file is required in the same directory.

#### Preload.rson Format:

```yaml
Paks:
[
    common_sdk.rpak,
    example2.rpak,
    ui_sdk.rpak
]
```

* Playlist Controlled Rpaks
  * These `.rpak` files are dynamically loaded/unloaded based on the selected playlist and level changes.
  * To use this system, specify the `.rpak` and related playlist names in the `mod.vdf` file.

{% hint style="warning" %}
The structure and usage of mod.vdf are described on the previous page.
{% endhint %}