npm-star(1) -- Mark your favorite packages
npm star <pkgname> [<pkg>, ...] npm unstar <pkgname> [<pkg>, ...]
"Starring" a package means that you have some interest in it. It's a vaguely positive way to show that you care.
"Unstarring" is the same thing, but in reverse.
It's a boolean thing. Starring repeatedly has no additional effect.