Information Technology Reference
In-Depth Information
pick them up, and anything you do in your email client is reflected
on the server. For example, if you delete a message, or create a new
folder for storing messages, that change is automatically reflected in
the email clients of every device that you use. The drawbacks are that
you may not be able to access old mail without an Internet connec-
tion and not every email provider offers IMAP accounts.
The POP and IMAP protocol are used only for receiving email; a com-
plementary protocol called
Simple Mail Transfer Protocol (SMTP)
is
used for sending email from a POP or IMAP account.
Simple Mail Transfer Protocol (SMTP)
A protocol used for sending email for a POP3
email account.
The line between HTTP, POP, and IMAP accounts has become blurry in
recent years, as more email providers have attempted to give customers
more options without making them change email account types. Most
providers allow customers the option of a web-based interface no matter
what type of email account they have, and some email clients can send
and receive mail from HTTP accounts, either natively or with some spe-
cial setup. In addition, some free web-based email services offer custom-
ers the option of paying a small amount for an upgrade to an account
that can be used as a POP or IMAP account.
Instant Messaging, Texting, and Chatting
Instant messaging (IM)
is another type of written message that is sent
over the Internet. As its name suggests, the message is sent immediately
rather than waiting for the recipient to log on to the service to retrieve
his messages. In many cases, the recipient will be online at the same time
as the sender and may respond immediately. The immediacy of IM makes
it more like having an online chat.
instant messaging
Sending and receiving
short text messages in real-time over the Internet.
Instant messaging is a
push technology
. That means that the messages
are pushed out to the recipient if he or she is logged in; it doesn't require
the recipient to do anything to check for new messages. In contrast,
email is a
pull technology
, because the recipient must actively check for
messages in order to pull the new messages to his computer. (The email
client can be set to automatically check for new messages at certain inter-
vals, so the email messages may seem to be arriving on their own, but it
is actually the client software pulling them.)
push technology
A technology that sends infor-
mation to a recipient without the recipient asking
for it each time.
pull technology
A technology that sends
information to a recipient only when the recipient
requests it.
Instant messaging requires you to have IM client software installed for
the service you are using. For example, Yahoo! Messenger's client soft-
ware for Windows appears in Figure 9.3. Other instant messaging clients
include AOL Instant Messenger (AIM) and Microsoft Lync (formerly
known as Microsoft Office Communicator). IM client software is avail-
able for Mac, Windows, and Linux operating systems, plus several smart-
phone and tablet operating systems.
Some instant messaging services include voice and even video chat capabili-
ties, as well as picture sharing. Including these features takes the applications
beyond simple instant messaging, into the realm of Voice over IP (VoIP)
and videoconferencing, both of which are covered later in this chapter.
Short Message Service (SMS)
The text
messaging technology used on cell phone
networks.
You can also send and receive instant messages on smartphones using a
technology called
Short Message Service (SMS)
, which goes through
your cell phone provider's network. This type of messaging is called
texting
.
texting
Sending and receiving short text mes-
sages in real-time over a cell phone network.