Spotlight index taking up space: rebuild it the safe way
Spotlight keeps a hidden index of your files. It is usually modest, but it can grow or get stuck. Here is how to check it and rebuild it safely, without deleting folders by hand.
Guides
Practical guides to Mac storage: what’s safe to delete and how to get the space back.
Articles, page 3
'Other' storage on Mac became System Data: what changed
The old Other category was renamed System Data in newer macOS. It is the same kind of catch-all, so the same checks apply. Here is what it held and where to look.
How to clean up the Downloads folder without losing anything important
Downloads is where forgotten files collect. Look at size and age first, keep what matters, and remove the rest in small steps.
Old installers, DMG files and update leftovers you can remove
A DMG is only the delivery box. Once the app is installed, it is usually safe to remove. Here is how to find them and what to check first.
Photo library too big on Mac: safe ways to shrink it
Check the size, then shrink it from inside the Photos app. Do not touch the library package in Finder, and back up first.
Messages attachments taking up space on Mac
Messages keeps every photo and video you send or receive. Check the size, then delete attachments or conversations in the app, not in the folder.