“A task’s duration represents the amount of time you expect it will take to complete the task. Project can work with task durations that range from minutes to months. Depending on the scope of your plan, you’ll probably want to work with task durations on the scale of hours, days, and weeks. Giving your tasks duration values is one of the benefits of using a scheduling tool like Project over a simple checklist or to-do approach to organizing work.
This topic will cover entering task durations, and the values available for durations, as well as entering dates and using elapsed durations.”