A task is an item to be completed by a specified date and time. When you assign a task to a user, the user can accept or decline the task, but until it is declined or completed, the task appears in the user’s Tasklist and on the user’s Calendar each day.
The Tasklist folder contains any tasks that you post or accept, as well as any other item you place in it as a reminder that the item needs to be acted upon.
To view more information about a task without opening the item, mouse over the task in the or Calendar view.