1. Command-Q to quit
If you are coming to Mac after a long tenure with Windows, then you might get tripped up when you click the red X in the upper-left corner of a window only to discover that the app is still running after the window closes. Unlike with Windows, the X button on a Mac closes the window but does not quit the app. To quit the app, use the keyboard shortcut Command-Q.
2. Function-Delete to forward delete
The missing backspace key on a Mac keyboard is another difference that might trip up Windows converts. Windows keyboards have a backspace key and a delete key. On a Mac keyboard, you get only a delete key. The delete key on a Mac, however, acts like the backspace key on a Windows keyboard. That is, it deletes the character to the left of the cursor. The delete key on a Windows keyboard does the opposite and deletes the character to the right of the cursor. To perform this maneuver on a Mac, press Function-Delete.
3. Command-Tab to switch apps
You can use the Dock to switch apps, but your Mac also has an app switcher. Hit Command-Tab to open the app switcher. While continuing to hold down the Command key, hit Tab again to move right through your open apps. Just above the tab key is the ~ (tilde) key; you can use it to move left through your open apps while continuing to hold down the Command key. You can also use the Command-Q shortcut in the app switcher to quit the app you have highlighted.
4. Command-Option-Esc to Force Quit
Think of it as the Control-Alt-Delete for Macs. If an app is not responding, press Command-Option-Esc to call up the Force Quit Applications window. Select the troublesome app and click the Force Quit button to kill it.
5. Command-M to minimize
You can click the little yellow dash button in the upper-left corner of a window to minimize it, but it might be easier to just hit Command-M to minimize the active window on your Mac. If you have multiple windows open of the same app, you can hit Command-Option-M to minimize all of them.
6. Adjust volume and brightness in smaller increments
When you use the volume, screen brightness or keyboard backlight brightness keys, you have 16 levels from which to choose. For finer control, hold down Shift-Option when adjusting volume or brightness. Each of the little blocks you see on the onscreen menu is sliced into quarters when you hold down Shift-Option for a total of 64 volume or brightness steps so you can get your levels just right.
7. Option-click to toggle Do Not Disturb
You likely use Do Not Disturb on your iPhone to silence alerts during certain times of your day or night. Macs also feature a Do Not Disturb mode, which you can schedule during certain hours via System Preferences > Notifications or manually activate via the Notification Center.
Do Not Disturb is oddly hidden in Notification Center. You need to click the Notification Center icon in the upper-right corner of your Mac and then scroll down a bit to reveal the Do Not Disturb toggle switch at the top. You can reduce this click-swipe-click process to a single click by employing the Option key. Just hold down the Option key when you click the Notification Center icon. When the icon is grayed out, Do Not Disturb is on; when the icon is black, Do Not Disturb is off.
8. Option-click menu bar icons
You can use the Option key with other menu bar items to access different or expanded menus. Option-click the volume icon and you'll get a menu that allows you to change the input source or output device. For the Wi-Fi and Bluetooth buttons, Option-click reveals more in-depth information about your network and connected devices, respectively. The Option key also works with third-party menu bar icons. Option-click the Dropbox icon, for example, and you can see how much of your storage allotment you have used.
9. Option-click the Apple button
On the other side of the menu bar, in the upper-left corner of your Mac, sits the Apple icon. Its menu lets you restart or shut down your Mac and view system information. If you press the Option key when the menu is visible, you'll notice the dots disappear from Restart, Shut Down and Log Out commands. No dots means the confirmation step is removed, so you can perform any of the three commands in one fell swoop.
The other change you'll see when you hold down the Option button here is the About This Mac changes to System Information. When you click About This Mac, you open a small window that shows an overview of your system. It also features a button labeled System Report that opens a second window with more detailed information about your hardware, software and network. With the Option key held down, the System Information menu item lets you bypass the overview page about your Mac and go directly to the system report.
10. Command-spacebar for Spotlight
I covered this one on my tips about Spotlight search, but it bears repeating because it might be the most useful keyboard shortcut on the Mac. Instead of clicking the magnifying glass in the menu bar to open Spotlight search, just hit Command-spacebar.