People, thank you all for your overviews.
I guess I have to go a bit off topic, here. Admittedly I'm not a Git master and I'm having an issue. I made my own brand new branch, checked out into it, I successfully applied a patch onto it. The status shows nothing to commit, the log shows the patch applied. But the affected files aren't changed, they are as they were. What's going on, here ? Thanks for any hint