MacBook clamshell mode (or closed-display mode) is an Apple-supported configuration that allows you to use your laptop with the lid closed while connected to an external display, keyboard, and mouse. This setup essentially transforms your MacBook into a desktop workstation, ideal for managing one device instead of two. 

How to Use Clamshell Mode (Key Requirements)
To activate this mode, your MacBook must meet the following requirements:

  • Power Adapter: Connected to a power outlet.
  • External Display: Connected and active.
  • Input Devices: A Bluetooth or USB mouse/trackpad and keyboard connected.
  • Action: With all peripherals plugged in, simply close your MacBook lid. The desktop will appear on the external monitor