Updated 06/01/18: Now that macOS 10.13.5 is out, we've updated our guide to show how to enable Messages in iCloud on the Mac.
Nearly a year after it was first announced, Messages in iCloud is finally available. All you need to enable it is iOS 11.4 on your iPhone or iPad.
You’ll almost certainly want to turn this feature on as it improves on the sort of half-baked syncing feature that was the only option in previous releases. Before, if you were signed into the same Apple ID on your iPhone and iPad, then the Messages apps on each device would simply show incoming messages at the same time. As you replied back and forth, each device updated the conversation threads in unison.
