Hierarchy of directories with source files such as CMake/C++ sources.
CMake starts with the CMakeLists.txt
from top of the source tree. This directory can be set by -H
in command line or by
Browse Source... in CMake-GUI.
This directory is mean to be shareable. E.g. probably you should not store hard-coded paths specific to your local environment in this code. This is directory that you want to be managed with VCS.