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 military, a messenger is an official courier.

Yahoo! Messenger is an advertisement-supported instant messaging client and associated protocol provided by Yahoo!. Yahoo! Messenger is provided free of charge and can be downloaded and used with a generic "Yahoo! ID" which also allows access to other Yahoo! services, such as Yahoo! Mail, where users can be automatically notified when they receive new email.

Windows Live Messenger

Windows Live Messenger, formerly MSN Messenger, is an instant messaging client for Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows Mobile, first released on December 13, 2005 by Microsoft.It is part of Microsoft's Windows Live set of online services. The current stable version is Windows Live Messenger 2008 (also known as version 8.5), which was released on November 6, 2007.For previous versions of this software called MSN Messenger, see MSN Messenger.

Google Talk (GTalk) is a Windows and web-based application for voice over internet protocol (VOIP) and instant messaging, offered by Google.Instant messaging between the Google Talk servers and its clients uses an open protocol, XMPP, allowing users of other XMPP clients to communicate with Google Talk users.Google has announced that a major goal of the Google Talk service is interoperability. (Internet Chat Relay)

mIRC is an Internet Relay Chat (IRC) client for Microsoft Windows, created in 1995 and developed by Khaled Mardam-Bey. Although it is a fully functional chat utility, its integrated scripting language makes it extensible and versatile.It is unknown if the "m" in mIRC stands for anything — Khaled's personal FAQ explains that "it quite possibly stands for 'moo', or perhaps even MU".mIRC ia easy to operate and downloading.there are so many versions of mIRC messanger. Online[AOL]
AOL is perhaps best known for its online software suite, also called "AOL", that allowed millions of customers around the world to access the world's largest "walled garden" online community and eventually reach out to the internet as a whole.AOL began life as a short-lived venture called Control Video Corporation (or CVC), founded by Bill von Meister. Its sole product was an online service called Gameline for the Atari 2600 video game console after von Meister's idea of buying music on demand was rejected by Warner Brothers.