iMessage

A secure messaging service that you can use to send and receive messages on your Mac, iPhone, iPad, iPod touch and Apple Watch.

If someone sends a message to your email address or phone number using iMessage, you receive the message on all your Apple devices that are set up to receive messages sent to that email address or phone number. When you view an iMessage conversation, you see all messages sent from any device, so you can keep in touch with someone wherever you are. See the Apple Support article Continuity features and requirements on Apple devices.

You need an Apple Account to use iMessage. If you’ve made purchases from the iTunes Store or App Store or you’ve signed in to iCloud, you have an Apple Account.