Twitter finally softens the rule of 140 characters which is in place since the service was launched in 2006. But beware, this announcement does not mean that you can write tweets of infinite length.
Say more about what’s happening! Rolling out now: photos, videos, GIFs, polls, and Quote Tweets no longer count toward your 140 characters. pic.twitter.com/I9pUC0NdZC
— Twitter (@twitter) September 19, 2016
Clearly, when you add a photo or photos (up to 4) to a message, a video, a GIF, or a survey, they are no longer counted in the number of characters. Ditto if you quote a tweet (quote retweet). By cons, URLs and references of people are still recognized in 140 characters.
To recall, the rule of 140 characters in Twitter was in 2006. At the time, the Tweets were also sent by SMS and they were limited to 160 characters. So the first 140 characters were reserved for the message and Twitter kept 20 characters for the user name.