Isn’t it just it a presence messaging on steroids? What about a free global SMS addressbook? Or a hyperlink-enabled persistent chatroom? To be fair, I don’t hear that last often, but summing up what Twitter is and what it does is challenging — especially in 140 characters or less. Twitter’s own “social messaging utility where people can communicate in real-time” comes close. Twitter’s creators know better than most what they’ve created and how it works.

Other takes on Twitter range far and wide:

• Caroline Middlebrook described Twitter as “an incredibly powerful marketing & community building tool.”
• In a long post that describes how he discovered Twitter and how SocialText is using it, Ross Mayfield called Twitter “mobile social software that lets you broadcast and receive short messages with your social network” aka, “Continuous partial presence.”
• Wendy Boswell writes that Twitter is a “mini-blogging platform that you can use to send messages of 140 characters or less to family, friends, or just the general Web community.”
• Dave Winer explains Twitter as a network of users on a microblogging platform with its own open-identity system and ecosystem.
• Ed Kohler posted that Twitter is “a social networking site based around text messaging.”

WhatIsTwitter.com is addressing the question by hosting a contest that asks you to explain Twitter in 140 seconds. (It runs through 6/23/08, if you’d like to enter.)

When I tweeted the question to the Twitter community, Robbert replied that Twitter was “a great way to get in touch and ‘meet’ very interesting people!” and Liz tweeted back that “Twitter is a window into other people’s worlds. Scholars can get insulated so it is nice to hear the ups & downs in other fields.”

In the end, however, I think a shade on Wikipedia’s current definition comes closest: a free distributed social networking and microblogging service that may be updated from the Web, IM, cellphone or a desktop client.

The question of what, exactly, you can DO with Twitter is something else altogether. The session at Enterprise 2.0 devoted to microblogging addressed exactly that question. The discussion was lively, both in person and on Twitter itself, as we could all see on the screen as Laura Fitton (@pistachio) Twittered about the event.

Even though at least one member in the audience questioned the etiquette of such an embedded distraction, with respect to her engagement with the rest of the panel, the bulk of the conversation between the other Twitterers in the audience and those present was inquisitive, supportive and engaged. You can see the various streams of conversation around the session and the conference in general at Twemes.com by using the hashtags #e20, #en20 and #ent20.

With the notable exception of Loren Feldman from 1938Media, the panelists supported the idea of Twitter or something like it (call it “X enterprise microblogging platform”) being both useful and present within an enterprise in the near future.

So what’s the story? Have I lost you yet? Do many of the terms above need further explanation? A colleague looked at me recently with a quirked eyebrow and asked me if I seriously expected her to ask conference-going IT professionals to “Tag their tweets on Twitter” and all I could do was grin.

Like so many emergent services and ecosystems on the Web, Twitter has evolved its own lingo. I’ve blogged about Twitter for WhatIs.com before, of course, but it’s worth reviewing the basics. Here’s a quick guide to get you started and give you some of your own”Twitter-fu.”

The Basics: For the novice Twitter user

By now, the story of how Twitter came to be has been extensively documented, so I’ll leave it to others to tell the tale. Check out this great video from Common Craft, Twitter in Plain English:

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You can update Twitter from Twitter.com, which is how the majority of users access the service, from instant messenger or by texting to “40404″ with a cellphone registered with the service. If you do use a cellphone, remember that there may be associated charges for text messages of .10 or .15 per message. Early adopters of the Twitter and the iPhone discovered to their chagrin that thousands of texts got quite expensive. If you’re planning on using your cellphone to tweet, seriously consider investing in an unlimited text messaging plan.

No matter what, you’ll need to register first. Choose the username that fits you, your brand, your company, service, product or simply your whim. Try to make it as short as possible; you want to reserve as much space as possible for others to use in replies, since they’ll need to include your username in a reply.

Here’s where one of the conventions that Twitter has introduced into the Web comes into play. Instead of remembering both a username and a domain name (johndoe@yahoo.com), all you have to do is remember a username (@johndoe). Just type in go to twitter.com, add the user name to the url and click “follow.”

If you want to publicly reply to a tweet from another user, just include @johndoe in your message and he or she will automatically see it. Just click “replies” on your Twitter page to see how has responded to you. You can also direct message another user by typing “d johndoe” — but only if they are following you. This is quite useful for conversation you don’t want the entire Web to be involved in.

There are other etiquette concerns, paralleling netiquette on the rest of the Web; read Chris Brogan’s post Considering Social Media Etiquette and Grammer Girl’s Twitter Style Guide to get a flavor of the conventions at play.

Ready to go? Start at the Twitter homepage, which includes a useful Twitter FAQ TwitterFeed. Each time you post to Twitter, it’s called a “tweet.” Each tweet has its own URL, just like a “normal” blog post has a permalink. Twitter’s 140 character limit means that brevity is crucial, so using URL shorteners like TinyURL.com is a must. You can make your first update just like a blog post on Blogger or WordPress. “Hello World” would work, if you’re stuck for inspiration.

Twitter isn’t much fun, however, if you’re just twittering into the ether. To get the most from the service, you’ll need to find some friends or find interesting feeds to follow, like @MarsPhoenix or @BarackObama. MC Hammer is out there too, by the way. You can always just search for people you know on Twitter or go to a user’s profile page if you already know someone you want to “follow.” Once you get rolling, you can use a service like WhoShouldIFollow.com to find more friends.

Following means that you’ll get all of that person’s updates, so choose carefully. If you choose to follow top Twitterers, expect to see a lot of messages. This is a great way to discover interesting new people, however, so even if you don’t follow @Scobleizer, @LeoLaporte , @JasonCalacanis, @KevinRose or other A-list bloggers or “cewebrities,” make sure to check their profiles to see who they’ve discovered. You can always unsubscribe if someone posts content or links you don’t want to see in your feed.

The other symbol you’ll see often is the hashtag, which is the Twitter version of a social bookmark. Think of them as a way to add your tweets to niche conversations, specific events or around products or services. Learn more at hashtags.org. I mentioned them earlier when I listed the various hashtags for the Enterprise 2.0 Conference. By adding a # sign and then a series of numbers and letters afterwards (try #beatLA, for Celtics-lovers) your tweets will be aggregated into the great conversation.

Twitter has opened its application programming interface (API) to the development community , which has responded by creating many desktop clients that you can use to update the service, manage your messages and friends.

To use my favorite client, Twirl, you’ll need to download Adobe AIR and install Twirl as a desktop client. Twirl includes a URL shortener and many other features that, in my humble opinion, richly enhance your Twitter experience. Twirl can also be configured to post automatically to Pownce and Jaiku, two other popular microblogging services. If you use a Mac, Twitterific might be a good fit, too.

Rafe Needleman has posted a terrific “Newbie’s Guide to Twitter” over at Webware.com, which I highly recommend if you’re still having trouble getting started.

Getting into the conversation: For the intermediate Twitter user

Now that you’ve gotten your feet wet, here are some more services to expand your horizons.

You can monitor whatever keyword you choose, like your name or your company’s brandname, at Tweetscan. Even if you don’t choose to use Twitter actively, this is an important component of brand and reputation management.

You can see threaded conversations with Quotably. This is a useful tool if you want to see an entire back and forth between users in one place.

Similarly, Summize helps you track Twitter conversations in real-time.

Use Mobile Twitter if you have a BlackBerry, Treo or other smartphone with a browser or try out Hahlo.com if you have an iPhone.

There’s a dedicated BlackBerry client called TwitterBerry too, which is worth looking into if you’re a “CrackBerry Addict.”

Quakk, Tiny Twitter, TwitToday and Twobile all work as clients for Windows Mobile 5.

Facebook has a Twitter application that embeds your tweets in your profile and allows you to tweet from within the social networking environment.

You can display your latest tweets automatically on your blog with an embedded widget, like this Twitter widget for WordPress or the Twitter Widget for Blogger.

Or, if you want to hook up your blog’s feed to Twitter, Twitterfeed will be helpful.

Watch Twittervision to see a mashup of a global Google Map and location-specific tweets.

Use TwitPic to share photos on Twitter.

For the Advanced Twitter User

If you’ve gotten this far and have been nodding your head all the time, waiting for something new, congratulations: Your Twitter-Fu is strong. The Twitter Fan Wiki should be your resource of choice, where new applications, services and software is aggregated and vetted by a strong user community. If you’re an alpha geek, make sure to check out the scripts page, which is chock full of geeky goodness.

I’m far from the first to try to explain what Twitter is an how it works, of course. Make sure to check out Tweeternet.com for an excellent explanation and outstanding list of Twitter tools.

If you’ve mastered the basic and intermediate tools and technologies, consider the following ways that Twitter has been put to good use:

• As a social justice tool, where people in critical situations can get the news out quickly
• As a crisis response and management tool (check out @RedCross)
• As a presence tool for emergency workers or individuals in a natural disaster zone

If you have questions, thoughts, additional resources, uses or any other response to this post, please use the comments. And, of course, Twitter about it. Do you think Twitter — or a client like it — is right for your business or enterprise? Let us know!

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While it’s true that there are many other SEO bloggers and a burgeoning industry in search engine marketing, none are quite so well placed within the search engine giants nor so willing to share best practices and commentary. Thanks for your contributions to the Web community, Matt.