This feature allows a 2017 iMac to be used as an external display for another Mac. Connecting the two machines with a compatible cable triggers this functionality, transforming the 2017 iMac into a monitor for the secondary device. For example, a MacBook Pro could utilize a 2017 iMac’s screen for a larger workspace.
The ability to repurpose the 2017 iMac as a secondary monitor offers significant advantages, particularly for users with limited desk space. It eliminates the need for a separate monitor while leveraging the iMac’s high-resolution display. This functionality was a key feature of iMacs released in that year, extending their lifespan and utility beyond their primary function as a standalone computer. Its availability reflected a trend toward more flexible and interconnected devices within the Apple ecosystem.