Com Apple Preference Keyboard

Option–Volume Up: Open Sound preferences. This works with any of the volume keys. Option–Shift–Volume Up or Option–Shift–Volume Down: Adjust the sound volume in smaller steps. Option–Keyboard Brightness Up: Open Keyboard preferences. This works with either Keyboard Brightness key.
According to the Language & Text preference pane, the shortcuts are: ⌘ - space (command-space) - previous input source. ⌥⌘ - space (command-option-space) - next input source. Of course these shortcuts are already being used by Spotlight, so if you have that active they won't work.
Feb 19, 2013 Type 'System Preferences'. You can either use option-; or type three periods. Type the menu command for which you want to set a keyboard shortcut in the Menu Title field. You must type the command exactly as it appears in the application menu, including ellipses and any other punctuation.

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I had been trying out settings and changed in System Preferences - Keyboard and the 'Keyboard' tab the 'Touch Bar shows' to be 'Quick Actions' - leaving that annoying 'Configure in' message up if there wasn't app content to override it. Try out the other options till it has what you want in it. Open System Preferences → Keyboard → Shortcuts; In the left menu choose: 'Services' In the right, scroll all the way down to the General, and assign your service some unique hotkey, I choose cmd+shift+L. It's not very fast or anything, but you don't have to run any app or go to the Preferences yourself.

Media box for macbook. If you own a new Apple magic keyboard or extended keyboard you may not realise how to use those extra function keys on the top right of the keyboard. You can set them up to launch and control applications. For example I have my f-19 key set up to toggle my Dragon Dictate microphone and I have f-18 set up to launch my Google Calendar calendar in a specific browser.

There are various ways to set up a shortcut. Let's go from the simplest (although limited) to the most versatile (but complex).

Within the app

Some applications allow you to set up your own shortcuts. You just go to Preferences in the app and you can select your own shortcuts from there.

System Preferences

If you go to System Preferences/Keyboard there's a tab that allows you to customize many system keyboard shortcuts. Here you can see I have set my F-1 and F-2 keys to adjust the screen brightness. But you can also use the extended function keys like F16, F17 etc.

Launch Apps or URLs

Reset administrator password macbook pro. You can launch applications or URLs directly from a function key.

The Apple way to do it is to set up an automator function and then assign it to a service and then assign that to a function key. I find that far too complex so I use an app called ‘Keyboard Maestro'. It allows you to set any key to launch any application or URL.

Here is what it looks like: (This shortcut opens my Google calendar.)

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Applications that won't let you assign function key

US Extended Keyboard - Apple Community

There are some applications that will let you set a keyboard shortcut using a modifier key (e.g. command-shift-key) but they won't let you assign a function key directly to their shortcuts. The workaround for these applications is to use Karibiner Elements to remap your function key to a different shortcut. Creating your own complex modifications is a little tricky, I'll leave you to read about it here:

Here is an example of where I have used Karibiner Elements to remap my f-19 key to shift-option-command-9 so that I can then assign a shortcut in Dragon Dictate to turn the microphone on and off:

So there you have it. Using Keyboard Maestro and Karibiner Elements you can map any key to any shortcut and even launch Applications or URL's using function keys.