Git interactive add

Git supports adding files at the wildcard level:

git add *.txt

and Git support adding specific files:

git add file1.txt

but Git also supports adding portions of a file through a mode called interactive (or patch mode) add:

git add -p *.txt

or

git add -p file1.txt

This prompts you, in sequential fashion, to stage, split (into smaller pieces), or skip each changed hunk of the change files that you've listed.