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Twitter is a free social networking and
micro-blogging service that enables its users to send and read messages known as
tweets. Tweets are text-based posts of up to 140 characters displayed on the
author's profile page and delivered to the author's subscribers who are known as
followers. Senders can restrict delivery to those in their circle of friends or,
by default, allow open access. Users can send and receive tweets via the Twitter
website, Short Message Service (SMS) or external applications. While the
service, itself, costs nothing to use, accessing it through SMS may incur phone
service provider fees.
The 140 character limit on message length was initially set for compatibility
with SMS messaging, and has brought to the web the kind of shorthand notation
and slang commonly used in SMS messages. The 140 character limit has also
spurred the usage of URL shortening services such as tinyurl, bit.ly and tr.im,
and content hosting services, such as Twitpic and NotePub to accommodate
multimedia content and text longer than 140 characters.
Since its creation in 2006 by Jack Dorsey, Twitter has gained notability and
popularity worldwide. It is sometimes described as the "SMS of the Internet"
since the use of Twitter's application programming interface for sending and
receiving short text messages by other applications often eclipses the direct
use of Twitter.
Twitter is ranked as one of the 50 most popular websites worldwide by Alexa's
web traffic analysis. Although estimates of the number of daily users vary
because the company does not release the number of active accounts, a February
2009 Compete.com blog entry ranked Twitter as the third most used social network
based on their count of 6 million unique monthly visitors and 55 million monthly
visits. In March 2009, a Nielsen.com blog ranked Twitter as the fastest-growing
site in the Member Communities category for February 2009. Twitter had a monthly
growth of 1,382 percent, Zimbio of 240 percent, followed by Facebook with an
increase of 228 percent. However, only 40 percent of Twitter's users are
retained.
Books on Twitter

Author: Leslie Poston, Michael Gruen, Laura Fitton
Publisher: For Dummies (2009)
Binding: Paperback, 288 pages

Author: Steve Cone
Publisher: Reed Seminars (2009)
Binding: CD-ROM, pages

Author: Adrian Dayton
Publisher: Ark Group (2009)
Binding: Paperback, 83 pages

Author: The Editors of Geekpreneur
Publisher: New Media Entertainment, Ltd. (2009)
Binding: Paperback, 376 pages

Author: Steve Helland
Publisher: Reed Seminars (2009)
Binding: CD-ROM, pages

Author: Idil M. Cakim
Publisher: Wiley (2010)
Binding: Hardcover, 224 pages

The Backchannel: How Audiences are Using Twitter and Social Media and Changing Presentations Forever
Author: Cliff Atkinson
Publisher: New Riders Press (2009)
Binding: Paperback, 240 pages

Author: Monica Jones, Steve Soho
Publisher: CreateSpace (2009)
Binding: Paperback, 162 pages

Author: Daniel Crenna
Publisher: Wrox (2009)
Binding: Paperback, 456 pages

Author: Todd Kelsey
Publisher: Apress (2010)
Binding: Paperback, 400 pages

Author: Hollis Thomases
Publisher: Sybex (2010)
Binding: Paperback, 432 pages

Author:
Publisher: Tebbo (2009)
Binding: Paperback, 200 pages

Author: Dusty Reagan
Publisher: For Dummies (2010)
Binding: Paperback, 384 pages
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Author: Adam L. Penenberg
Publisher: Hyperion (2009)
Binding: Hardcover, 288 pages
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Author: Joel Comm
Publisher: Wiley (2010)
Binding: Paperback, 272 pages

Author: Darren Barefoot, Julie Szabo
Publisher: No Starch Press (2009)
Binding: Paperback, 280 pages