Sidecar in macOS turns your iPad into a second display, but it's limited to certain Macs and iPads. Thankfully, a few ...

Duet Display lets you use any Android device as a second screen for your Mac, whether wired or wireless, giving you extra space for multitasking.

Enter so-called "second screen" apps, software applications on tablets or phones that synchronize onscreen action with supplementary information such as behind-the-scenes footage, costume design ...