Slowly but surely Twitter is being transformed: new functionalities, plenty of user interface tweaks, promoted tweets, "while you were away" highlights, the list goes on. It's not the platform it once was but we must embrace change.

The latest change is rather big: in addition to a recent change allowing for group conversations, now there is no longer a 140-character limit to private messaging.

This is a sensible move because Direct Messages were never meant to be pithy public declarations. Invariably, they would spill into multiple parts, which was frustrating.

Now, you can have proper chats, much like Facebook messaging. Don't worry about public tweets: they are still confined to 140 characters so your timeline isn't about to get messy.

https://blog.twitter.com/2015/removing-the-140-character-limit-from-direct-messages