I have looked at various threads for this answer and google and I keep getting people just asking what did they do wrong and it talks about settling and I do see tips how to.  What I want to know is what is settling exactly and what is the purpose of it?  I made a grooms cake this past weekend, baked the cake the day of, cooled, leveled, torted and decorated and nothing happened.  Can someone explain bc I seriously cannot find an answer for it and a friend of mine that is a professional pastry chef had never heard of it either.

Here's one member's explanation:

http://cakecentral.com/t/633571/my-newest-trick

ATorthank you I did see this post when I did a search but is really did not answer my question it just says that it avoids bulging in that cake but I do not see how just making a two layer cake have bulging and from what I see and some of the other host is that some people just did not do the damn thing they put their filling in I guess my question was more what exactly is settling and why is it necessary because some people say they don't do it some people say they do it but I would kind of like some reason behind exactly what's that link is not how to do it but thank you I do appreciate it. sorry I am doing speak and text so if some of this sounds odd my apologies but it won't let me edit any words

Settling is the release of air or liquids caused by pressure/weight and a sign of instability.

A cake is a "structure" so you need to know your materials before you "build". If you use a dense, pound cake, pudding added recipe... you make not "settle" because you don't have excess air, and it supports the weight of the fondant and decorations. Another baker, with a lighter cake, and more force on top (decorations, thicker fondant application, etc.) could have settling, even making the same design.

Worse, settling often indicates a break down of materials (cake), so you need to worry about the cake itself (reads crumbling/ sliding/ falling apart).

Ajhhhhhhhh ok that explains it.  That was great and thorough explanation I appreciate it.  If just doing a simple2 layer cake I would not think it is needed but more so for tiering cakes no?  Not sure i like the tile method but any other suggestions?

You really just need to try it because it depends on your recipe, climate, fillings, etc.

The "dryer" and "denser" the cake, the less settling you should have. Of course, I am also assuming that the cake is baked properly (not under cooked). 

I live in Texas, so I adapt to excess heat often, but rarely have a settling issue because I use a doctored cake mix with pudding so I get a dense cake.

Yes, with a standard 2 layer cake, you should not have an issue, unless you are trying to get a 2 pound topper on it, or you use really THICK fondant. 

ASettling is usually because as the weight of the cake pushes the icing down, it will bulge out. Usually it's ever so slight. I let my cakes sit out 5 hours and pop them into the frig. Then the next day I scrape the bulge with a large plastic bowl scraper.

The thicker, less soft, the icing, the less bulge. (or none at all)