Twitter is testing a change to one of the most iconic parts of the social media network - tweet length is being doubled from 140 characters to 280 characters for a limited number of users according to a post on the company's official blog.
Twitter has had a 140 character limit for the entirety of its existence, but that longstanding icon of the platform is now changing. A limited number of users are being upgraded to double the standard length so that the company can gather data on how it's used. You can see the expanded character count in action in this tweet from Geoff Keighley regarding 2018's The Game Awards:
https://twitter.com/geoffkeighley/status/912904518689525761
The core reason for the changes is backed by Twitter's own data and the way languages work. Certain languages - namely Japanese, Chinese, and Korean - are able to convey much more meaning in fewer characters. As an example, 0.4% of Japanese tweets hit 140 characters and 9% of English tweets meet that same number. To their reckoning, this means that English-language users are hitting a wall more often in terms of what they would like to write in a single tweet.
The expanded character count will be applied to all languages other than Japanese, Chinese, and Korean and is purely a practical concern. The company feels that it will be a positive change and that the data they have backed up the decision, but they are nonetheless being cautious and testing this out in limited numbers. They also speak to concerns that people may have emotional attachments to the number of 140 characters, something that has been replicated across other sites like Imgur or expanded upon by alternatives to the platform such as Gab (which has a 300 character limit for its posts).
Twitter had been gradually changed what exactly 140 characters means. The social media platform announced changes to the scheme in May of 2016 such as usernames no longer counting towards the limit, images no longer eating up 23 characters to post, and the ability to quote tweets directly.