https://blog.twitter.com/express-even-more-in-140-characters
In the coming months we’ll make changes to simplify Tweets including what counts toward your 140 characters, so for instance, @names in replies and media attachments (like photos, GIFs, videos, and polls) will no longer “use up” valuable characters. Here’s what will change:
Replies: When replying to a Tweet, @names will no longer count toward the 140-character count. This will make having conversations on Twitter easier and more straightforward, no more penny-pinching your words to ensure they reach the whole group.
Media attachments: When you add attachments like photos, GIFs, videos, polls, or Quote Tweets, that media will no longer count as characters within your Tweet. More room for words!
Retweet and Quote Tweet yourself: We’ll be enabling the Retweet button on your own Tweets, so you can easily Retweet or Quote Tweet yourself when you want to share a new reflection or feel like a really good one went unnoticed.
Goodbye, .@: These changes will help simplify the rules around Tweets that start with a username. New Tweets that begin with a username will reach all your followers. (That means you’ll no longer have to use the ”.@” convention, which people currently use to broadcast Tweets broadly.) If you want a reply to be seen by all your followers, you will be able to Retweet it to signal that you intend for it to be viewed more broadly.
