What does the mainData contains? How to minimize it?

Hello,

I was wondering what does the mainData file contain?
(The mainData file is a file in the folder after a build of a Windows player,)

Actually I would like to minimize it and I don’t how I can do that.

Edit:

Here is the output after a build:

Textures      24.6 mb	 6.0% 
Meshes        63.8 mb	 15.6% 
Animations    4.5 mb	 1.1% 
Sounds        0.0 kb	 0.0% 
Shaders       277.3 kb	 0.1% 
Other Assets  1.8 mb	 0.4% 
Levels        294.3 mb	 71.8% 
Scripts       2.7 mb	 0.7% 
Included DLLs 16.2 mb	 3.9% 
File headers  1.9 mb	 0.5% 
Complete size 410.2 mb	 100.0% 

What is contained inside the levels?
I only include one scene in my build.
Are the asset bundles in my Assets folder automatically added to this?

Thx

It’ll contain all your game data, so scripts, audio, textures, meshes. As an experiment, backup your project and then delete all your textures from the Assets folder (and any folders beneath this). Then build the game. Does the size of the mainData change? Obviously the game will no longer be textured, but will tell you how much space they take up.