As you log completed tasks (such as calls, meetings etc) with contacts, it's helpful to keep detailed notes so they are easy to refer back to.
There are two ways to open these expanded details:
The first way is with "View / Edit" which will open the edit modal for your completed task, revealing the complete notes for the task:
The second way to view the complete notes is with "Show Full Details":
An advantage to "Show Full Details" is that you can continue to interact with your contact record while referencing the notes.