Mod

Mod is short for modification, or, in this case, game modification. Mods are used to alter one or some of a game's features, or even to introduce new ones. Mods are a form of custom content in that they must be downloaded and their file(s) must be placed properly. However, they are not in-game objects such as clothing or new decorative objects, though some mods use an in-game item to enable or disable their features.

This distinguishes them from "hacked objects". Mods mainly alter gameplay values or add/change already existing features. For example a mod could allow teenagers to WooHoo and become pregnant.

Examples of small mods would be phone plugins for The Sims, mods such as the Less Addictive Espresso Bar mod that affects how strongly an object advertises, or making the homework bar be complete faster.

Example of big mods would be Awesomemod and Macrotastics.

Since recent Sims games make more menu items available when using Testingcheatsenabled, many mods from older games have been seen as not worth remaking.

Some mods, like hacked cameras for The Sims 2, are not in package format and are not installed in the player's downloads folder, but somewhere else. These mods are known as config(uration) mods.

Altering actions
Mods can allow Sims to perform illegal actions and actions that they are not supposed to do or have such as a Child cooking food and a Teen being able to WooHoo.

Mods can also allow you to use actions/features that you cannot usually do (Similar to cheats such as Moveobjects).

However, some actions were formally 'illegal' in older versions. For example in Fast Lane and prior, you can only put pools on the first floor but as of Late Night, they can be put on any floor. Also in Medieval, version 1.3 allows 360 degrees rotation on all lots.

Mods can also change the behavior of the game as well.

Dangers of Using Mods
Mods, when they are programmed, installed and used correctly, can be safe to use without risking damage to game data or saved games. However, improperly installed mods or mods that do not work correctly can result in corrupt data, saved game losses, and severe glitches. That's why it is always good to take extra precautions and backup saved game data, like whole neighborhoods.

Some mods can corrupt objects or even cause malfunctions in the game code, resulting in one or more of the neighborhoods disappearing, which requires the game to be re-installed completely. See Load game error for problems related to neighborhoods.

Modders are not generally malicious, and trouble with mods as often arises from errors on the players' behalf as on that of the modders'. For example, Awesome Mod's Configuration Tool is designed so that players who do not take the time to read instructions have the option to select a checkbox that will turn their installation of The Sims 3 into a "Big Fiery Ball Visible From Space", or "BFBVFS". Basically this is a trick for catching out irresponsible Simmers. Players should always read the instructions surrounding a mod, and never use options if they're not clear on what they do.

Many mods, when installed, conflict with other mods. This is especially true for core mods; only one core mod can be installed at a time. A mod designer may or may not be aware of these conflicts, so it is important to be careful when installing multiple mods. Additionally, some mods may corrupt saved games or game data if they are uninstalled incorrectly. If a mod must be uninstalled in a particular manner, the documentation that accompanied the mod should explain this. Mods that add additional skills in The Sims 3 are known to cause damage to sims who have earned a skill which was recently deleted. This will cause the player to have to delete their saved game.

Also, players are advised to check for updates every time they buy a new expansion or stuff pack. Out of date mods can cause save game files not to be loaded properly. Also, there is a chance that the game will be destroyed if it is ran with and out of date core mod. Patch 18 fixed the issue at some rate by not prompting the player if any out of date mods are installed.

Starting with The Sims 3 High-End Loft Stuff and The Sims 3 Design & High-Tech Stuff, the player is told to disable Custom Content prior to updating or installing a new version such as The Sims 3 Ambitions.

Similar to cheats, mods also allow users to use 'illegal' actions (Such as deleting the Mailbox or Sims and a Teen able to WooHoo which the player cannot do) which can or may cause problems in the game as the userf/Sims are not supposed to use these actions.

Another issue is that mods created with Pets would cause an older game to crash. For example, a player's game which was loaded with an object created with the Pets expansion pack, would crash an Open for Business game.