Use tasks if you are looking to notify a user of a submitted activity or have them follow up on a specific item.
You can create a new task in a few different ways.
Every time you use one of your apps and submit an activity
Work Flow & Routine Tasks
When users are automatically notified upon every submission or if the amount of submits are not reached given a specified time period.
Search for the "Work Flow" & "Routine Tasks" articles to learn more
The dashboard overview allows you to view all activity in chart format.