Example:
this is the Assets Catalog. The Asset catalog include:
OBJ (objects)
SND (sounds)
SPR (sprites)
Rooms (levels)
Script (general code)
Tileset (big sprites)
Shaders (light modification)
PS (Particle system)
Sequences.
This image is from Game Maker but is the same for all game motors
GameMaker use VisualGML but Unity use C variations (C,C++,C# etc)