Add-ons, or Mods, are user-created content.

They can either add content into the game or alter the game's look/feel.

Types of Add-ons/Mods:

• Custom Map or Campaign - a user-created level (or levels).
  
  
• Weapon Modification - New weapons are NOT added into the game--the preexisting weapons are "covered" with a custom skin (the appearance); given different animations for firing, shoving, reloading; or given a new set of sounds.
  
  
• Custom Item Skins - Like the weapons, items are given a new look.
  
  
• Custom GUI - The HUD (the health bars, ammo counter, and items on the sides of the screen) is redesigned with either new images, a new layout, or both. Neun GUI is an example of a GUI modification.
  
  
• Custom Survivor Skin - Similar to weapon mods, new survivors are not added. Rather, the survivor(s) is given a new look. However, the original survivor usually retains their voice/lines.
  
  
• Mutations - custom gamemodes with a specific set of and rules and different gameplay.
  
  
• Custom Sound/Music - The voices of the infected are changed, or the default music is replaced with a new track. For example, some mods change the background music that plays when the Tank spawns. Others may change the music played at the end of a campaign.
  
  
• Other - color correction mods (change light color of the default maps), blood/decal/zombie texture mods, etc.

While the Workshop is an easier and faster way to download and manage add-ons, not every add-on is available on it. However, it is not too difficult to install them manually.

• Step ONE - Pick an add-on to download. While add-ons can be downloaded from anywhere on the internet, sites like http://www.l4dmaps.com/, http://www.moddb.com/games/left-4-dead-2/mods, or http://l4d2.gamebanana.com/ are good places to start.
  
  
• Step TWO - Download the add-on and extract if needed. All add-ons for Left 4 Dead 2 are .vpk files. If the downloaded file has a .zip or .rar extension, the .vpk file needs to be extracted from it first. Use an extractor program (ex. WinRAR, 7Zip) to extract the .vpk file from the archive.
  
  
• Step THREE - Install. Double-click on the .vpk file. After a few seconds, a message box should appear. If everything went correctly, it should confirm the installation of the add-on.

What a successful installation may look like. "Add-on" is replaced with the name of the add-on installed.

• Step THREE (ALTERNATE) - Install directly. Open the "addons" folder. Once again, it can be found in the following locations:
  
  For 32-bit editions of Windows: C:\Program Files\Steam\SteamApps\common\left 4 dead 2\left4dead2\addons
  For 64-bit editions of Windows: C:\Program Files (x86)\Steam\SteamApps\common\left 4 dead 2\left4dead2\addons
  
  Place the .vpk into this folder.
  
  Add-on won't install? If nothing happens when the .vpk file is opened or something similar, try either: downloading the add-on again or finding the same add-on from another source.
  
  

The workshop is the easiest and most convenient way to download, install, and manage add-ons.

Getting to the Workshop:

Method ONE: through Steam - Go to Left 4 Dead 2 in the Steam Library. From there, scroll down a bit to find the "Steam Workshop" section. Press "Browse the Workshop".


Method TWO: through the in-game browser - The Workshop can be accessed while playing Left 4 Dead 2. While in-game, open the overlay with SHIFT+TAB. In the top right corner of the screen, there should be a few highlighted links. Click "Workshop".


Methord THREE: from the "ADD-ONS" menu - Click on the "Browse Workshop" link at the bottom of the add-ons menu screen.

• Step ONE - Select on Add-on. Click on an add-on to be sent to its download page.
  
  
  
• Step TWO - Download. To download an add-on, click on the green button labeled "Subscribe".

After downloading enough add-ons, conflicts will probably arise. When two add-ons conflict, one of them has to be disabled.

• Step ONE - Go to the in-game add-ons menu. From the main menu, click on the "ADD-ONS" button.
  
  
• Step TWO - Enable/Disable the add-on. Clicking on the add-on from the list on the left shows its description, title, and author on the right. Conflicting add-ons are highlighted in red. To enable or disable the add-on, simply check or uncheck the box on the left of each add-on in the list. NOTE: Disabling an add-on does not remove it.

The method to remove an add-on depends on how the add-on was installed.

If the add-on was installed manually:

• Step ONE - Navigate back to the "addons" folder. Again, it can be found in the following locations.
  
  For 32-bit editions of Windows: C:\Program Files\Steam\SteamApps\common\left 4 dead 2\left4dead2\addons
  For 64-bit editions of Windows: C:\Program Files (x86)\Steam\SteamApps\common\left 4 dead 2\left4dead2\addons
  
  
• Step TWO - Remove. Delete the addon from the "addons" folder, but DO NOT remove anything in the "workshop" folder. See the next section to remove add-ons downloaded through the workshop.

• Step ONE - Go to the Workshop home page. From there, look at the right side menu. In the "Your Items" section, there should be a "Subscribed Items" link. Click on it.
  
  
• Step TWO - Unsubscribe. - A list of the add-ons that are subscribed to should appear. Click on the grey "Unsubscribe" button beside the unwanted add-on.

Q: What are collections?
A: Collections are a bunch of add-ons put together in a group. Anyone can create them, and any add-ons available on the workshop can be put into them.

Q: How can I create a collection?
A: To create a collection, go to the Workshop home page. Below the Left 4 Dead 2 logo are several tabs. Click on "Collections". A list of collections created by users will appear. On the right hand side, search for a blue button labeled "Create Collection". The rest is simple.

All add-ons shown are owned by their respective authors.