Git tracking differs from staging

I learned some Git principles and judo:

• tracking differs from staging:
  • i.e.git commit -a stages and commits already-tracked files, and new files won’t be committed;
  • git add . tracks and stages.
  • by definition, files are tracked only when they are first staged/committed. There is no “track but not stage” for new files
• git diff is “staged - working directory”. git diff –staged is “commit - staged”.
• git status -s gives a concise description of what’s untracked, modified, and whether the modification is staged or not.
• the “/[name]” ignores things in the current directory.
• “[name]” ignores things of a given name in all directories… more powerful than expected