Exchanging 
messages in realtime between two or more people. Unlike a dial-up system such 
as the telephone, instant messaging (IM) requires that both parties be logged 
onto their IM service at the same time. Also known as a "chatting," 
IM has become very popular for both business and personal use. In business, IM 
provides a way to contact co-workers any time of the day, providing they are at 
their computers. Thus, IM is often used as a way to avoid telephone tag, whether 
the communication continues as text messages or winds up as a traditional phone 
call. 
 
              Instant 
Messaging Vs. E-Mail
E-mail and instant messaging are often used in a similar 
manner, but e-mail is not realtime, and there can be delays of several minutes. 
Like e-mail attachments, IM systems generally allow for file transfers. Also like 
e-mail, some systems let you send messages even if the recipient is not currently 
online. IM is expected to promote IP telephony by allowing users the option of 
switching from typing to speaking (from text chat to voice chat) if they have 
a headset attached to their computers. 
              Buddy 
Lists
 In order to set up an instant message, you have to add the usernames 
of the people you want to message with to your "buddy list" (friend 
list, contact list). When they log on to the Internet with their IM software, 
and provided they have not configured themselves as "invisible," you 
are instantly alerted. When they log off, you are also notified. Each system has 
its own method for blocking incoming and outgoing messages.