Add-on

Add-ons or expansions (also called expansion packs) are content created for games that is released separately from the main game release. Downloadable content (DLC) is a specific form of add-on distributed through the internet.

The first game in the Fallout series to feature downloadable content was Fallout 3.

Falllout 3 add-ons are activated in the 'fallout 3 launcher,' the same place where you can configure the full graphics settings, but under the 'data files' option. Without addons you'll see only one row with the main fallout 3 game with a check next to it, with add-ons you should see an extra row for each add on, put a check next to each one to enable it. In the game, the addons should each pop up a message stating that they're loaded. Most will also have an associated radio signal which will become available at the time the message pops up.