• Apple did not give this functionality out of the box because the iPad versions were not designed to be used as a second display for a Mac or PC.
• Duet Display, AirDisplay, iDisplay, and Splashtop XDisplay are four programmes worth considering if you want to use your iPad as a second display with your Mac or PC.
• With one app on the iPad and a companion app loaded on the 'paired' computer, all four apps perform efficiently in the same way.
• Duet Display is now compatible with Macs running OS X 10.9 (Mavericks) or later, Windows 7 or later, and all iPad models running iOS 10 or later.
• Earlier versions of iDisplay only supported Wi-Fi connections, however the current version supports both direct cable and Wi-Fi connections.
• AirDisplay uses Wi-Fi to link an iPad to a Mac. Direct cable connections are not supported, and the current version does not support Windows.
• Splashtop XDisplay is a newcomer to the game, but it comes from a developer with a lot of expertise with iOS business apps.

Read More: What are the differences between the displays on different regular iPad models?