Many people don't know what Twitter is. Some people have accounts and don't know what to use it for. A few have accounts, use them but still cannot define what Twitter is.
This is my personal take on Twitter. I'm not gonna explain the concepts, just what they do for me.
Discussions on Twitter are a lot like gossip, except they are open to the audience of the intertubes. Short messages are prone to triviality and sometimes that's all people see when looking at Twitter and dismissing it shortly after. However, brevity is the soul of wit. I've been at times frustrated with the 140 characters limit but it proved to be a powerful creative mechanism and one of the reasons Twitter works.
One of the most frequent uses of Twitter among the tech crowd is following conferences. Conferences that are overseas, that you cannot reach, even items you may have missed from the topics in the other hall. If 50 years ago it would take several weeks before you read a newspaper reporting on a conference on a specific topic, you can now follow as it unfolds. Extrapolate this to important news, sports, or any kind of event and you will see it ripple through Twitter's streams faster than anything else.
Because of the character limit and simplicity of Twitter's interface, I think it brings an intimate way of publishing. A celebrity needs staff to maintain a Facebook page, never mind an entire website. 140 characters can be typed in little enough time so that everyone, no matter how busy, can share their thoughts with the world. In the time I've followed some favorite actors of mine (or any kind of celebrity), I've been surprised by the level of candor and openness Twitter's discussion achieves.
The "It's not Facebook" factor
I've opened a Facebook account at my family's requests and kept it to share links from this blog. Compared to Twitter, I feel I am lost in a sea of videos, photos, and games. Every time I login on Facebook, I approve x numbers of "Friend" requests, block an ever increasing number of idiotic games and ponder at the amount of time people waste on it. While I am not sure which way the information flows in Facebook (it's all a big wall to me), I can definitely identify that in Twitter. You don't "Friend" someone on Twitter, you voluntarily "Follow". A quite important distinction. If you want to follow what someone says, it means the content produced by that person is important to you.
There are quite a few wordsmiths on Twitter that condense relevant, witty nuggets into 140 characters but looking at my stream I see about 80-90% of tweets being links passed through. An opinion in a few words with a link from a person you respect give that link a lot more weight. Following some intelligent people turns Twitter into a clever filter for the internet. This is also why many Twitter clients have first-class browsers included in them. In fact, I am now checking first my Twitter feed for news and my Google Reader account after. An important part of Twitter is something which evolved from the community to be later included as a platform feature. The Retweet. This is Twitter's echo, gossip and reach all into one. One person posting the value content is retweeted by its followers to their followers and so on. Like an echo traveling at the speed of light (and mouse clicks) you can now gauge how important some news is by how many retweets it had. Why do retweets work better than any other sharing mechanism? Because you are actively following the person who retweets. Someone retweeting has deemed this worthy and there's a good chance you will pass that along to your followers saying "Hey guys, this is worth checking out. Trust me!". I think this social graph of trust is Twitter's greatest strength.
There are many ways in which people use Twitter. This is mine. What do you get out of it?