Can someone inform be about the Sims 3 Mods?

So, I'm a very frequent Sims 3 player. If you go on my profile, most of my questions are about the Sims 3. Recently, in the search of some information about the sims 3, I came across sites that kept referring to "Mods"? Please excuse my ignorance, but I tried to acquire information by researching, but I kept getting sites that just asked me to download crap.

So, could someone please inform me: What are "Mods"? Custom content? I don't get it. How do they work? Who creates them? Just any basic information about it that you can give me will be appreciated. Also, are they safe? Anything you know about them, inform this Sims 3 simpleton! Thanks. :DCan someone inform be about the Sims 3 Mods?
Mods are short for modifications. They alter the games features and can also introduce some but they are not made by the company that makes the game but by the users. So they are sort of unnoficial. There are many different mods for almost all computer games and for the sims there are mods that can make teens have woohoo or that can take the blur off of the sims when they are taking a shower. There are some dangers of using mods. If you use mods that are made improperly your game will not load or it will get corrupt. I am using some mods and they are from trusted websites and are safe to use.

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