iMessage

iMessage is Apple's proprietary, end-to-end encrypted messaging service, delivering rich media and advanced features exclusively across iOS, iPadOS, macOS, and watchOS devices.

iMessage is the secure, native messaging protocol for the Apple ecosystem: it launched with iOS 5 in 2011 and operates within the Messages app. The service utilizes end-to-end encryption, ensuring only the sender and recipient can read the content, and it syncs seamlessly across devices (iPhone, Mac, iPad). Key differentiators include the blue bubble for iMessages (data/Wi-Fi) versus the green bubble for standard SMS/MMS. Users leverage features like Tapback reactions, full-resolution photo/video sharing, inline replies, and screen effects. The platform also supports group chats, Memoji, and advanced functionalities like editing or unsending messages (iOS 16 and later).

https://support.apple.com/messages