The MacOS treats files which start with a period (.) as a hidden file. Say, something like .gitignore. And there are times where you want to actually see these hidden files. To do so, you can run some Terminal commands that affect the system. OR you can do a simple key command. Like so:

⌘⇧. will toggle the AppleShowAllFiles setting

This way you can turn them on/off quickly and easily without mucking in the Terminal.