A chat app refers to a text or video messaging application. See text messaging and video chat. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction requires permission.

The new messaging app takes design cues from Apple's iMessage, which uses blue chat bubbles for iPhone users and green bubbles for everyone else.

LONDON — A magazine journalist’s account of being added to a group chat of US national security officials coordinating plans for airstrikes has raised questions about how highly sensitive ...