Sorry, Sidney, but I had to modify your post. As Pam said in this very thread:
They can be very dangerous and cause a great deal of damage to your game, which is why we don't allow them to be specifically discussed or linked here.
Another reason we don't allow them to be discussed is that there are many that are designed to break the game's Teen Rating. As Carl's forum has always been a family friendly site, many of these mods are not exactly appropriate for discussion here, either. The one you mentioned (almost by name, no less) did precisely this.
But the question was "What is a mod," not "What mods exist." Since this wasn't specifically answered, allow me to do so:
A mod is a 3rd party program (meaning that it's coded by someone who doesn't work for the company that made the game) that modifies existing functions or adds new functionality to a game. Most computer games have mods of some form or another available on the internet, and The Sims 3 is no different in this respect. Mods for most games are relatively harmless, and in rare occasions actually add balance to a game that seriously lacked it. However, mods for The Sims 3 are anything
but harmless.
If you talk to mod creators for any length and ask questions about how things work (and I have done both), they will inevitably respond to at least one by saying "I don't understand why/how that works, but it does." The Sims 3 is a
very complex program. This is why it has some comparatively hefty hardware requirements, and is one of the main reasons that it is a bit unstable. It's easy to change one minor thing and have it alter how another completely unrelated process works...or break it entirely. And this is all done by the people who wrote the game in the first place, and understand how it works better than anyone else possibly could. Mods are written by someone
other than these people, who may very well be inadvertently tampering with a system that they don't understand.
If anyone tells you that a mod for The Sims 3 is safe, they are lying to you. For proof, all you need to do is look at the original forum thread where the download is available. This thread will be 20-30 pages long (or even longer) with users asking the designer for help in solving the problems they are having with it. They have also been directly linked to corrupted game saves and even corrupted game files, which can cause the game not to run at all.
And this is not to even mention that, without exception, any time you download an authorized EA patch, every mod in existence becomes instantaneously obsolete. You then have to remove them all, wait for the designer to upload an updated version of that mod, download it again and reinstall it.
To me, there is no possible "added functionality" that anyone could offer that would be worth all of this trouble.
