how to upgrade OS 10.9.5 to latest version

Back up your data, check your applications for compatibility, and depending on which Mac model you have, click on El Capitan, High Sierra, Mojave, Catalina, Big Sur, or Monterey.

32-bit software won't run in Catalina and newer; download and use Go64 to scan for it. To check general compatibility, click here and look your programs up.

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Same question with same answer from Mavericks https://discussions.apple.com/thread/253527608