One of the best things about Twitter is the fact that you don't need to use their website to access it. Twitter's API (application programming interface) allows any person with a little programming knowledge to write their own tweeting tools and twitter applications, letting users interact with the data that Twitter's service provides without having to use the Twitter website itself.

There are many kinds of Tweeting applications - some are "clients" which allow users to read their followers' tweets and post their own Tweets; other Twitter tools allow Twitter to integrate with other websites and applications, like those that synchronize Facebook status updates with Twitter tweets. Since Twitter charges no fees to use their service or write tweeting tools, there's no shortage of twitter applications out there.

Twitter tools are available on a variety of platforms - some are designed for PC's running Windows, others for Mac. Many Tweeting tools run on the Adobe Air platform, which is designed to let a single application run the same way on PC's, Macs and Linux computers. Twitter applications are also widely available for mobile platforms like iPhone, Android and Windows Mobile. Many of these mobile Tweeting applications are paid, while others are free. There are advantages and disadvantages to both.

It's hard to resist the lure of free Twitter applications - after all, they're free. There are a number of good tweeting tools available for free - TweetDeck, Seesmic Desktop, and Twhirl are three excellent free tweeting tools. Although these twitter tools have a solid following, they don't always have the full range of features that paid twitter applications do, and often a Twitter tool that's free on the PC costs money to use on a mobile platform like iPhone.

One problem with free tweeting applications is that they sometimes disappear without much warning. Since the developers often don't earn any money from programming and distributing them, financial pressures and time constraints can lead to developers quickly abandoning twitter tools - even those that have a large following.

On the other hand, you sometimes don't get what you pay for with paid Twitter applications. With so many free tweeting tools available, many Twitter users can get by perfectly well without needing to use a paid application. However, for Twitter power users who need to be able to access multiple Twitter accounts or who want access to advanced analytics and statistics about their followers, sometimes a paid application is the way to go.

The best way to decide whether to use a free or paid Twitter application is to sit down and make a small list of what features you require in a tweeting tool, then compare a few different tweeting applications until you find the one that matches your list the closest. For normal users on computers, that application will probably be free. For mobile users, however, hardcore Twitter users will often be willing to pay a few dollars to get the best tweeting tools and the cleanest presentation. How much you're willing to pay depends largely on how much you use Twitter - for business users, paid Twitter applications are almost always a necessity.