A messenger is a person employed in business to convey messages, official dispatches, telegrams, letters, or parcels, and go on special errands as part of their duties. In the government and/or military, a messenger is an official courier.Messenger may also refer to:
Computers
An instant messaging client or service in general, or specifically one of the following services:
AOL Instant Messenger, an ad-supported instant messaging and presence computer program, published by America Online
BitWise IM, an instant messaging client published by BitWise Communications, LLC
Google Talk, an instant messaging client published by Google
Miranda IM, an opensource instant messaging client released under GNU GPL
MSN Messenger, the Microsoft instant messaging client preceding Windows Live Messenger
Windows Live Messenger, an instant messaging client published by Microsoft
Windows Messenger, the instant messaging client bundled with Windows XP
Yahoo! Messenger, an instant messaging clie
Source:
http://en.wikipedia.org/wiki/Messenger