It is the digital footprint left by everything you say and do online, as well as everything others post about you. Your digital reputation is influenced by the people and sites you follow, the content you post, like, or share, and the comments you make.

Positive digital reputation:

Bryan's shared post about the canned food drive is encouraging because it demonstrates Bryan's involvement in his community.
Bryan's post wishing Alan luck.
Negative digital reputation:
Sharing the party photo of his friends holding cups, as people who see the photo may not realize what kind of party it was and may assume he and his friends were behaving inappropriately or were drinking alcohol illegally.
He is posting negative comments on Matt's social media and writes disrespectful things to his classmate.