Cyrus’ tongue-in-cheek attitude is why fans adore her and detractors loathe her. It’s also why her transfixing Twitter feed gets people talking. Sometimes the conversation can be provocative. Other times it can be downright weird (see: inexplicable video of Cyrus twerking in a unicorn onesie.) And on occasion her tweets, for better or for worse, even become the news. And while there’s no doubt the 21-year-old musician uses Twitter for self-promotion, she also uses the social network to rally fans around causes she cares about. —David Winograd