Twitter introduces an automatic link shortening on Twitter.com to help you make things fast. As you all know, Twitter messages are limited to 140 characters. If someone wants to share a link in a message, the link itself takes most of the available characters, so you need to depend on third-party URL shortening service like bit.ly, TinyURL, etc to shorten the link.
Now twitter rolling out this feature to twitter.com. Anyone can tweet using the new t.co short URL. (This feature is currently available to twitter employee accounts, but soon will be available to anyone).
The working is just like this. Paste a link into the Tweet box, compose your Tweet and you hit the “Tweet” button, it will shorten the link to 19 characters.
In addition, to increase its user’s security, Twitter is testing a method to cut back on malicious linking. According to an official blog post, twitter will show a shortened version of the original link, so people will know which site the link points to. Moreover, if users click links that are reported as malicious, twitter direct them to a page that warns them. (via)