Use Software Update

- Choose System Preferences from the Apple menu , then click Software Update to check for updates.
- If any updates are available, click the Update Now button to install them. Or click “More info” to see details about each update and select specific updates to install. You might be asked to enter your administrator password.
- When Software Update says that your Mac is up to date, the installed version of macOS and all of its apps are also up to date. That includes Safari, Music, Photos, Books, Messages, Mail, Calendar, and FaceTime.
- To automatically install future updates, including for apps that you got from the App Store, select “Automatically keep my Mac up to date.” Your Mac will notify you when updates require it to restart, so you can always choose to install those later.
Update the software on your iPhone, iPad, or iPod touch
Learn how to update your iPhone, iPad, or iPod touch to the latest version of iOS or iPadOS.

How To Update Mac Os High Sierra 10.13.6
Learn more
- If your Mac is using an earlier version of any Mac operating system, you should install the latest Apple software updates, which can include important security updates and updates for the apps that are installed by macOS, such as Safari, Books, Messages, Mail, Music, Calendar, and Photos.
- 古いMacでは「macOS High Sierra」のサポート対象外となり、macOS High Sierraをインストール出来ないMacがあります。 ワタシの使っているiMac「 iMac Early 2008 」も、「macOS High Sierra」のサポート対象外となっています。.
- Learn how to get updates for earlier versions of macOS that don't include Software Update preferences.
- You can also use the App Store to update apps or redownload apps that came from the App Store.
- Learn which macOS your Mac is using and how to upgrade to the latest macOS.
- When your Mac is connected to a Personal Hotspot, large updates don't download automatically.
Update Mac Os X 10.5.8 To High Sierra
MacOS High Sierra; macOS Sierra; OS X El Capitan; OS X Yosemite; OS X Mavericks; OS X Mountain Lion; Mac OS X v10.7 Lion; Mac OS X v10.6 Snow Leopard; Mac OS X v10.5 Leopard; Mac OS X v10.4 Tiger; Mac OS X v10.3 and earlier; Mac OS X Technologies; Classic Mac OS (OS9, OS8 & System 7) Photos for Mac; QuickTime; Safari; Front Row.
