Managing personal tasks with due date, start date, priority, tags etc.
Definition of task management according to Wikipedia (en):
Task management is the process of managing a task through its life cycle. It involves planning, testing, tracking and reporting. Task management can help either individuals achieve goals, or groups of individuals collaborate and share knowledge for the accomplishment of collective goals. Tasks are also differentiated by complexity, from low to high.
Effective task management requires managing all aspects of a task, including its status, priority, time, human and financial resources assignments, recurrency, notifications and so on. These can be lumped together broadly into the basic activities of task management.