For many years, people have traded sports cards -- thick pieces of paper that had pictures of sports stars.

多年来，人们一直在交换体育卡——印有体育明星照片的厚纸片。

Sports cards are still popular, but some sports leagues are moving into the digital world, as well.

体育卡仍然很流行，但一些体育联盟也在向数字领域进军。