Over the past few years, Internet usage has gradually moved from computers to smartphones and tablets. Social media usage in particular has become an on-the-go activity. According to recent Nielsen data, American Facebook and Twitter users already spend more time using the services on their smartphones than they do on computers. It took Facebook some time to realize that its future is mobile but when it did, the company build a great mobile ad business in no time. The Nielsen data suggests that to Twitter, mobile is even more important than it is to Facebook. 85% of Americans' Twitter usage happens on smartphones, indicating that Twitter is becoming a mobile-only company and needs to build its business accordingly.