Can My iPad be a Second Monitor?

If you have a Mac running macOS Catalina or later, Sidecar, which enables communication between your computer and tablet and extends the same desktop environment, will let you use your iPad as a second display. This capability is restricted to only some Mac and iPad models, which is a disappointment if you have an older device or a Windows PC. A few third-party apps however can fill the gap on all the devices that cant run Sidecar.