Passbook is helping Major League Baseball transition away from traditional physical tickets to digital ones. In in an initial test run with four teams in the final two weeks of the season, Passbook was used for 12% of electronic tickets, which account for over two thirds of all ticket sales. While the convenience of Passbook has delighted fans, it also seems to have struck a chord with the league as a whole. Though Passbook itself doesn’t hold personal information, the apps that feed Passbook, in this case, the MLB iPhone app, do. Using the app, teams and parks can more specifically target advertising, or make specific offers to loyal fans.