As with all the Sims versions it was fairly easy to add content to the game.  Sims 4 is no different.  I use custom content extensively on the Sims themselves,where I rarely use the content supplied by EA itself.  The majority of the content comes from The Sims Resource (TSR).  I also cruise a bit on My Sims4 Blog once in a while for when I’m searching for something special.

For mods, they come exclusively from Mod The Sims.  Mods if you don’t know is modifications to the game engine itself, either by modifying via the XML data files or by using python scripts.  MC Command Center along with the no-mosaic mod are two must have mods, but that is  just my opinion.   There are quite a few mods available, the issue I have with them is the possibility of breakage between game updates and keeping a tab on what mods I have can get complex.

For the houses and venues that I share (upload), I spend time in keeping them custom content free (#nocc) and will continue to do so.  There are a few houses still in my library that do contain CC,  but they will be removed one of these days. I rarely download houses or venues, since building is something I enjoy doing myself, and when I do, it is because I want to know how did they do that.