Twitter has released a much-awaited feature: longer tweets. There is still the 140-character limit but there are some parts of your tweet that won’t be counted. These include media attachments (GIFs, videos, images, and polls), quote tweets (except if you actually put the link on your own and not using the Twitter feature), and even usernames when replying to a tweet. For that last point, it doesn’t have to be just one user. If you reply to multiple people, their usernames won’t be counted as well.
Source: The Verge