What is a "mesh" body?

[CNAstudent]

Could somebody please explain what the term "mesh" means in second life to me? I purchased a tatoo & i looked up why i couldnt add it to my avatar, but supposedly its for mesh bodies only. I dont understand what I need to do. 

[Rolig Loon]

There are two basic avatar body styles in Second Life.  Both are technically "mesh" structures (well, everything in SL is a mesh structure, after all), but the difference is that until recently, all bodies were based on the same "classic" mesh model.  Any newer ones that are not based on the classic model are refered to as "mesh" avatars.  If you look in your inventory's Library >> Clothing >>> Initial Outfits folder, you will find a rather large collection of potential avatars, some of which say "(mesh)" next to them.  Ones that don't are "Classical" avatars.

So, you have two choices.  You either select one of the mesh avatars in the folder (or buy one from a merchant in SL) or you buy a tattoo and other attachments that are designed for a Classical avatar body.  If it were my own choice, I would take the cheaper route and use a classical avatar body.  That's also a little easier to get used to until you've been in SL for a while.

Read more at

https://community.secondlife.com/t5/English-Knowledge-Base/Controlling-your-avatar-s-appearance/ta-p/700709

EDIT :  or take a look at Nalates's response in this thread >>> https://community.secondlife.com/t5/Mesh/Advice-Needed-for-Mesh-Avatar-Complete/m-p/2984176 for a really good (although more technical) explanation.