The inspection reports include directives that are not used or not required and can be safely removed.

Detect completely unused

an include directive is unused if declarations from it are not used in the whole translation unit at all.

Detect not directly used

an include directive is unused if declarations from it are not used in the file directly. This works best with the "Include What You Use" policy.

Detect not required

detects the minimal set of include directives enough to keep the file compilable. Other #include directives are unused.