When no external display is connected to your MacBook, closing it puts the entire laptop to sleep. It’s pretty simple. East With an external display, mouse, and keyboard connected, closing your MacBook allows you to use it in “Clamshell” mode—that is, you can operate the computer using the external display and controls.
This default behavior should cover most use cases, which is probably why Apple doesn’t allow much configuration. But maybe you want your MacBook to go to sleep when you close it, even if there’s a display connected. Or maybe you want the computer to turn off completely? If that’s the case, check out Clamshella free app that lets you choose.
The app sits in the menu bar and gives you five options. There’s the default behavior, which we described above, and then four more. Sleep will put your MacBook to sleep as soon as you close the lid, even if another display is connected. This is great if you use an external display but never use your MacBook in clamshell mode. Beautiful.
Close goes one step further by turning off your computer completely (this requires installing a system-wide background helper). Shutting down your computer is great if you want to preserve battery life, but it’s also extreme: you risk losing any unsaved work and will have to restart the laptop. However, if you’re using your MacBook in a public place, this is the safest option: it’s very difficult to access a Mac without the password if it’s completely turned off.
These two features are pretty easy to understand, but there are two more that are a bit trickier. The first of these, Keep external displays on and avoid sleep modewill keep the screen on and also prevent your screens from going to sleep. This is a good idea if you want something to remain visible on your screen even if you are not actively using the laptop.
The next option, Turn off screens and prevent inactive sleepwill turn off your displays but not your device. This is ideal if you want your MacBook to continue playing music or downloading files when the display is off. Note that this won’t happen if you’re not connected to power, meaning you don’t have to worry about this option draining your battery.
All of these options are very handy, which is why I’m surprised that Apple doesn’t offer a way to configure them in Settings. The good news is that Clamshell is free and does the job well.