The Task List view is one of the transactional views (Calendar and Gantt views are also transactional views). It lists all tasks in a schedule or template. It provides a hierarchical (parent-child) view of tasks. You can filter the list of tasks to display only the ones in which you are interested.
For example, if you want to quickly and easily see a list of tasks in a hierarchical view and edit some information directly, you can use the Task List view.
By default, the list is sorted by the Starts column. You can click a column heading to sort by that column. Parent tasks are indicated by an arrow, which you can click to expand or collapse the display of their children.