Twitter announced on its blog that its link-wrapper system (a URL shortener called t.co) will take up more tweet space starting in February 2013, which means less space for any tweet containing a hyperlink.
You'd think the Twitter URL shortener would be going in the other direction, right? How we'd love to have more room for our messages, not less. But unfortunately, this change will mean you lose two extra characters in each tweet containing a hyperlink.
T.co Wrapper Getting an Overhaul
What's being changed is the technical implementation of Twitter's internal URL-shortening system, t.co. It kicks in each time you put a long URL beginning with "http" into a tweet, replacing it with a shorter URL that starts with "http://t.co" and is followed by a string of characters. (FAQs about link-shortening on Twitter.)
In the existing t.co system, any "http" link you put in a tweet takes up 20 characters out of Twitter's allowable 140 characters, and "https" links take up 22. Now http links will take up 22 characters, and links starting with https will gobble up 24 characters.
Twitter's blog said the changes will effect on February 20, 2013, giving developers of third-party apps a little more time to update their code. Read the official announcement here.
You'll still be able to use an external link-shortening system like Bitly or TinyURL, which provide users with more analytics than Twitter's system does. A lot of people still use those because they generate short links that work on other websites, not just Twitter's. But Twitter wraps ALL links using t.co, including shortened ones.
The vast majority of Twitter users let Twitter wrap their URLs for them rather than using a third-party shortener, so this space grab will have a widespread effect on users. Many complained loudly in tweets denouncing the news system this past week.
History of Twitter URL Shortener
Twitter introduced its mandatory, automated t.co link-shortening system in 2010 partly for security reasons, to help protect users from links to malicious websites or to material with harmful code. Another major reason was to give Twitter more insight into link behavior on its site. The rollout went systemwide in 2012. At first Twitter only truncated or shortened links, but eventually it "wrapped" them with a new url starting with t.co. Initially the t.co wrapper applied only to super-long URLs but eventually it was applied to all URLs in tweets.
The way t.co "wrapping" works is simple. People enter a URL into their tweet, and Twitter automatically shortens it when the tweet is posted live. You don't get to see the shortened URL while you're composing your tweet, but you do see the impact of the shortening calculated in the tweet-character count that Twitter displays as you type your message.
The change was particularly controversial for users who had developed their own proprietary link-shortening URLs or who already used third-party shorteners, since it essentially meant Twitter would shorten already-shortened URLs. A lot of people wanted to continue using their own shortener systems since they provide more robust analytics than Twitter's t.co system does.