Why Tasks and not Calendar?

There is sometimes some confusion as to the difference between tasks and calendar entries. But there is a large conceptual difference between tasks and calendars entries.

Briefly stated, calendar events are either "be there" or "date based" events. A "be there" event is anything that requires your physical presence at a specific place and time, such as meetings, appointments, prearranged telephone calls, vacations, sports events, etc. "Date based" events are events that happen on a specific date like holidays, birthdays, anniversaries, the start and end of classes at school, etc.

By contrast, tasks are things you need "to do" either alone or with others. They can be simple tasks that need to be done as a single step, or more complex tasks which require concerted effort over a period of time, may have sub-tasks, target dates for start and completion, etc. Generally you use the tasks list for specific tasks (or duties) you must perform and for which you want to track their status through to their completion.

As an example, consider the task of building an addition to a house. Adding an entry such as "build room addition" in your calendar on a specific day is of little use -- it may remind you to start the task on that day but it won't help you identify the various stages needed, schedule those stages by priority or timeline, plan for completion of the various stages or the entire project, or track the status of both the sub-tasks and the entire project as it progresses. It is a good fit for a task list rather than a calendar entry.

On the other hand, a lunch date is a better fit for the calendar. You only need information about where to be, when to be there, and who else will be there. You don't require sub-tasks, progress tracking, status reports, etc.