Hashtags is an advanced, but easy-to-use Twitter feature. The reason they are called hashtags is because they start with a # symbol. Here are some examples: #rejectprop8, #dragmetohell, etc #rejectprop8 is a hashtag that people used when talking about Proposition 8. Users can put “#rejectprop8″ and then other Twitter users can easily find their tweets by looking at all the #rejectprop8 tweets.

Many Twitter applications, mobile and desktop, allow users to find hashtags. Some applications call them “trends” instead of “hashtags”. Most applications will keep track of the 10 or 20 most popular hashtags at any given time, so it really lets you see what people are talking about at any given time.

When the movie Drag Me to Hell came out last week (05/29/09) in the United States, many Twitter users began talking about it, and the #dragmetohell hashtag quickly jumped to the top of the Twitter top hashtag list. When looking at the #dragmetohell hashtag, I found tweets about the movie. Some contained links to reviews, some were just tweets about the user going to the movie that night, some were tweets suggesting that their friends should go see the movie, etc.

Many celebrities that have a lot of followers are very good at starting trends a.k.a. hashtags. They will post about #something and that #something will become very popular in a short amount of time. Many of their followers will begin talking about that topic and it will become widespread very quickly.

Another advanced feature is “re-tweeting” and if celebrities re-tweet tweets from their followers and those tweets in turn contain hashtags, the topic’s popularity will in a sense compound. For example, when Blink 182 member Mark Hoppus began posting about #rejectprop8, he also re-tweeted some tweets that his followers sent about #rejectprop8, and that in turn boosted the popularity of the #rejectprop8 hashtag. Soon it was at the top of the list, and Mark tweeted about how he was amazed how fast it climbed to the top of the list.

If you’re tired of reading the news to find out what’s going on, consider checking out the Twitter trend lists. Apps that let you easily follow the trend list are Twitterific, Tweetie and Twittertrend.

TIP: To make a schreen capture of your iPhone, simply press and hold the “Home” button at center bottom of the iPhone, then press and release the “Sleep” button on top right of the iPhone. This causes the iPhone to “flash” white briefly and the image is added to your “camera roll” on the iPhone!

What makes Twitter particularly interesting is the variety of mobile Twitter application on the iPhone. All of them offer different features, and each tries to stand out from the crowd by offering its own assortment of Twitter functionality.

My favorite of the applications I have tried, is Twitterific by “iconfactor.” It offers the most attractive user interface and is by far the easiest to use. Runner-up, in my mind, is Tweetie, which offers a little more functionality but is not quite as easy on the eyes. They both open up the world of Twitter to the user.

They offer even more features than the Twitter website itself! In my opinion, until somebody has used these apps, they have not experienced Twitter and will not understand why it is interesting or even worth using.

It is such an interesting way to communicate and interact with others. Even celebrities! Celebrities love using Twitter because they don’t have to “be friends” with other users like similar social sites would require, such as Facebook or MySpace.

What is challenging about Twitter is that it limits what you want to say to 140 characters, and even text like web links are included. So if you include a web link, you’re pretty limited in what you can say in your “tweet”. That is why a myriad of URL shorteners has sprung up, to make your web liks as short as possible. TinyURL was one of the first to offer this, but their name is actually too long…I use http://z.pe you cannot get any shorter!

A rare feature in Twitter iPhone applications (even the official Twitter site does not offer this) is the ability to see a list of tweets that were written about any particular user. Reading these tweets is often very interesting, especially if they are written to a celebrity. You get to see how normal people would talk to a celebrity, and you can see how the celebrity responded as well. Some Twitter applications allow you to see conversations (or “threads”). This is another advanced feature that not all Twitter apps offer.

A lot of people are talking about Twitter lately. But Twitter works best when people are just using it rather than talking about it. If people talk about it without using it, it could be in danger of becoming a fad.

I personally think that Twitter has a bright future. There are so many improvements and innovations that could be made. When the day comes that I can record a video with my iPhone and then post it on Twitter for all my followers to see instantly, I will be in geek heaven and will more than likely abuse that feature.