At the galaxyview page you see an icon for notices next to the player. If you click on that icon you can add a notice for this player which will be displayed whenever you view a system where the player is located.
Notices can be used to store a report of the largest fleet you have ever seen or to collect his online activities to establish a raid strategy.
Notices can be adjusted / viewed by every member of your alliance who has an account at the galaxyview.
You can use BBCode inside the the notices.