Summary
Apple frequently releases software updates for macOS, iTunes, Safari, and various other Apple managed apps.
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Overview
Apple releases bug fixes, vulnerability patches, feature improvements and even OS upgrades for macOS and its apps via Software Update. Although your Mac automatically checks for new updates once a week, prompting you if there are new updates available, you can manually check to see if there are any available macOS updates or upgrades.
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See Also
Keep your Mac up to date
How to upgrade macOS
Software Update Management on University Macs
Troubleshoot OS Updates on macOS (Faculty/Staff)