Twitter has been working on numerous ways to improve conversations on its platform, from both an ideological standpoint and in terms of the user interface. Today, the company has begun testing a prototype app called twttr with a select number of participants, which features a redesigned UI for tweet threads and conversations.
The new app was announced by the company in a tweet, and it's only available for a few of those who signed up for the chance to try it. Instead of the current presentation for tweets and their replies, the new UI presents them in a fashion somewhat similar to that of messaging apps, where each tweet and reply looks like a message.
It remains unclear when the new design will roll out to all Twitter users, or if twttr will become more widely available prior to a general release of the redesign. In the meantime, it's still possible to sign up for the test program, though it won't get you instant access to the new app. You'll need to wait for the company to approve your participation and make the app available to you.