Mark a Task as completed by right-clicking the task flag and when the shortcut menu appears click Mark Complete.
In Simple List view completed tasks show as pale grey with a line through them and the Completed box is checked.
Task lists may be displayed in a variety of ways, choose the best for you from the Current View group on the Tasks Home tab. Choose from Detailed, Simple List, To-Do List, Prioritized, Active, Completed, Today, Next 7 Days, Overdue, Assigned and Server Tasks.
Sort Tasks by clicking on the column headers, so to sort by order of priority click on the Priority column header.
A red exclamation mark indicates that the Task is high priority, while a blue arrow indicates low priority.
When there is no mark beside the task it has a normal priority setting.