The Other storage on your Mac is composed of files that do not fall into clearer category labels: “applications, backups, audio, movies, backups, and photos”. This is the space taken up by plug-ins, documents, and caches stored by OS X.
These files are not harmful to your Mac but if they accumulate too much space to your hard drive. Over time, it can slow down computer performance. It is a very broad list of items, including things like the following:
- Documents and file types, (PDF, doc, PSD, etc.)
- Archives and disk images, (zips, dmg, iso, etc.)
- Personal and User data
- System folders of macOS, (temporary files, swap, voices, etc.)
- User library items (Application Support, iCloud files, screen savers, etc.)
- Cache items (browser cache, system cache and locally-stored message media content)
- Fonts and App accessories
- Application plugins and app extensions
- Various file and file types not recognized by Spotlight
- Everything else that does not fit into the main macOS categories
"Other" is not always junk or useless files, but we recommend removing the useless content from this category.