Tasks are activities that need to be completed. They are assigned to a user in your database (because, let's be honest, they won't get done if they're not assigned) and can be associated to a constituent. A task summary is shown on the dashboard, and you can click through to a list of tasks. Tasks associated to a constituent also show on their timeline.
Tasks are created from the dashboard, the task list, or a constituent profile. You may opt-in to receive email notifications when tasks are assigned, updated, or overdue. You can add attachments to tasks. When tasks are finished, they can be marked as completed, saved as an interaction (if they are associated with a constituent), or archived. Of course, you can change the assigned user and reactivate a finished task.