Implementing hearts on its Periscope livestreaming service was just the first step for Twitter that is bringing them over to two of its other services.
Twitter felt that the star was a strange symbol to newcomers, and the heart would be a more recognizable symbol for liking something, so they are adding hearts to Twitter and Vine, replacing the star for favorites on Twitter and the smiley face on Vine.
— Twitter (@twitter) 3 novembro 2015
Twitter probably wanted the same symbol for liking something across all of its services, and it chose hearts from Periscope. This is rolling out to Twitter on Android, iOS, the web, TweetDeck, and Twitter for Windows 10 starting today.