Install macOS 10.12 Sierra on your Macs and iOS 10 on your iOS devices and you’ll get a cool new feature: Universal Clipboard. As you’d expect from the name, Universal Clipboard transfers anything you copy to all your devices so you can paste anywhere. Copy some text on your iMac and a few seconds later you can paste it on your MacBook Air, your iPhone, or your iPad. Or copy an incoming phone number in the Phone app and paste into an email message on your iMac. Universal Clipboard even works with graphics and videos.

Neither Sierra nor iOS 10 provides any interface for Universal Clipboard at all. You can’t turn it off or configure it in any way. In other words, it should just work. But what if it doesn’t? It turns out that six things must be true for Universal Clipboard to work. Miss any of these and Universal Clipboard will fail to copy the clipboard contents from device to device without warning. The requirements are as follows:

1. Any Macs involved must have been introduced in 2012 or later, or, in the case of the Mac Pro, 2013 or later. Choose  > About This Mac to check your Mac’s age. Since Sierra runs on most Macs introduced since late 2009, Universal Clipboard won’t work on some older but otherwise Sierra-capable Macs.
2. All Macs must be running macOS 10.12 Sierra or later, and all iOS devices must be running iOS 10 or later.
3. All the devices must be on the same Wi-Fi network. This requirement can be tricky since devices might join different Wi-Fi networks if several are available. On a Mac, look in the Wi-Fi menu bar menu, and on an iOS device, check Settings > Wi-Fi.
4. Each device must have Bluetooth enabled and be within Bluetooth range of the other devices. That’s usually about 30 feet, but it’s safest to assume that both devices need to be in the same room. On a Mac, check in System Preferences > Bluetooth. On an iOS device, open Settings > Bluetooth.
5. All the devices must be signed in to the same iCloud account, and that account must be the primary iCloud account on each device. To see which account is signed in, on a Mac, look in System Preferences > iCloud. On an iOS device, check Settings > iCloud.
6. Handoff must be enabled. On Macs, turn it on in System Preferences > General. On iOS devices, the necessary switch is in Settings > General > Handoff.

If you still have trouble after verifying that your setup meets the six requirements above, make sure that your Wi-Fi connection is working well on each device, and that each device can connect to the Internet. If either of those isn’t true, Universal Clipboard may not transfer the clipboard contents.

When it’s working, Universal Clipboard takes just a few seconds to move the contents of the clipboard from device to device, and the transferred item remains available for pasting for about two minutes. It’s a subtle, but welcome addition to the Apple experience.