With Apple's Sidecar technology, you can wirelessly pair your iPad to your Mac and freely drag apps and windows between both devices. Here, I break down all the steps for turning on Sidecar and using an iPad as a second monitor. You can either extend the Mac operating system to your iPad or mirror the iPad to your Mac. Most Mac and iPad models support Sidecar, as far back as 2016, but here's the compatibility just in case. On a Mac, open Settings > System Preferences > General and toggle on Allow Handoff between this Mac and your iCloud devices.