# File Extensions

<p class="callout info">This is a list of the most common files you'll edit when creating a mod. It is recommend that you download the tools to [extract the game resources](https://wiki.eternalmods.com/books/beginners-guide-how-to-create-mods/page/extracting-resources "Resource Extraction Tools") before continuing. That way, you can reference these files as you go.</p>

## .decl File Extension

.decl files (short for "declaration") are the most commonly used files in Doom Eternal modding. They are a form of script or "pseudo-code" that is interpreted by the game engine. Many of the variables and numeric values used by the game are defined in these files. They can be edited with a text editor.  
**<span style="text-decoration: underline;">  
Filepath:</span>**  
`<resource>/generated/decls`  
**<span style="text-decoration: underline;">Example:</span>**  
`gameresources/generated/decls/weapon/weapon/player/rocket_launcher.decl`  
&gt; File to edit the Rocket Launcher.

## .entities File Extension

The .entities file contains all of the data in a map/level except geometry — if you want to make a level mod, you will need to learn how to edit the .entities file. These files are stored compressed, and require [a tool to decompress them](https://wiki.eternalmods.com/books/beginners-guide-how-to-create-mods/page/text-editor#bkmrk-decompressing-tools%3A "Tools for decompressing .entities files"). After that, the file can be edited with a text editor.  
  
**<span style="text-decoration: underline;">Filepath:</span>**  
`<resource>/maps/game/<campaign>/<level_name>/<level_name>.entities`  
<span style="text-decoration: underline;">**Example:**  
</span>`e1m1_intro_patch1/maps/game/sp/e1m1_intro/e1m1_intro.entities`  
&gt; Level file path for Hell on Earth.

## .tga File Extension

These are texture files. If you want to create custom skins or other artwork, you will most likely be editing these .tga files. Not everything "visual" is a .tga file. Many of the game's particle effects, lighting effects, and other visual effects are controlled by .decl files instead.  
  
Texture editing software is required to edit .tga files.  
  
**<span style="text-decoration: underline;">Filepath:</span>**  
`<resource>/models and <resource>/art`  
**<span style="text-decoration: underline;">Example:</span>**  
`gameresources/models/monsters/arachnotron/*`  
&gt; Texture files for the Arachnotron's model.

<p class="callout info">Despite the name, the ".tga" files used in Doom Eternal are not actually .tga (targa) images. You will need to use a tool such as SAMUEL or VEGA to extract them in a usable format (.dds, .png, or .tiff).</p>