Mac storage basics · Caches, logs and temporary files
How do I show hidden files in Finder?
Short answer: Press Shift-Command-. (period) in a Finder window to show or hide hidden files. They appear dimmed; avoid deleting ones you don't recognise.
Press Shift-Command-. (period) in any Finder window to toggle hidden files on and off. Hidden items appear slightly dimmed.
Hidden files include system folders and "dot" files that apps use for settings. Seeing them helps when tracking down space, but most of them are small and some are required, so avoid deleting hidden items unless you know what they are.