iMessage is a messaging service developed by Apple that allows users to send text messages, photos, videos, and other files to other Apple users. It was first introduced in 2011 and is available on all Apple devices, including iPhones, iPads, Macs, and Apple Watches.

iMessage uses end-to-end encryption for all messages and also offers features such as group chat, read receipts, and the ability to send voice messages. It also integrates with other Apple apps, such as Siri, Apple Music, and Apple Pay.

In addition to personal messaging, iMessage also offers a variety of features for business communication, including the ability to send and receive money through Apple Pay and the ability to create custom iMessage apps for specific businesses or brands.

iMessage is available for free on all Apple devices and can also be accessed through the Messages app on Mac computers. While iMessage is known for its security and privacy features, it is only available to users who have an Apple device and cannot be used to message users on other platforms, such as Android or Windows.