Courtesy of Twitter
Starting now, when a user replies to another person's (or people's) tweet, their username won't count toward Twitter's signature 140-character limit as it has since the beginning of the service.
Twitter teased the change May when it announced several such tweaks in the works, like not counting images toward the character limit, and began testing it in October.
Why it matters: Over the last couple of years, Twitter has attempted to boost its stagnating user growth by tweaking its product to make it easier to understand for new users and easier to use for existing ones.