[hefty]

>there's a file that's been modified that's unrelated to what I'm trying to commit

What if those unrelated changes are in the same file as a bunch of related changes that you've already made? Do you undo all the changes you've made in that file apart from the random bug fix and then commit, or leave them intact resulting in that bug fix commit containing changes that are unrelated to the fix?

[nickhuh]

In that case you'd want to use "git add -p" which allows you to pick only parts of a file to stage for a commit. It can be crucial in crafting a really solid project / commit history.

For even more complex cases you could use "git add -i"; however, that command can be tricky to work with and I find it's usually not to helpful to get that far into the weeds.

[erichocean]

Atlassian has a nice UI for doing that visually, too. Super easy.

Honestly, people for whom the command line UI is "too difficult" should just use a GUI client. That's the target audience for them.