add_subdirectory

add_subdirectory(
     dir 
    [EXCLUDE_FROM_ALL]
)

dir

The CMakeLists.txt file from this subdirectory will be executed next.

EXCLUDE_FROM_ALL

Whether targets added in this subdirectory should be built during make all.

This is a cmake builtin command. For detailed information, check the cmake documentation:

cmake --help-command add_subdirectory