How to restore your Mac to an older version of OS X

Don't want to install El Capitan on a Mac you're restoring? Here's how you can install an older OS.
    Related:
  • Operating Systems
  • OS X Mavericks
  • OS X Mountain Lion
  • OS X Yosemite
Glenn Fleishman’s most recent books include Take Control of iOS & iPadOS Privacy and Security, Second Edition (covering iOS 15/iPadOS 15), Take Control of Your M-Series Mac, and Take Control of Securing Your Mac. In his spare time, he makes Tiny Type Museums. He’s a senior contributor to Macworld, where he writes Mac 911.