You can use the timeline to capture notes or assign reminders for internal purposes.
To add a note, click the ‘Add note’ bar on the top of the timeline. This will open up a text field for you to capture notes.
To add a reminder, check the box ‘Add a reminder’ when adding a note. This will allow to select a date in future when this task will be due.
The notes and reminders you add is internal and will not be visible to the customers.