AutoSum is a feature in Microsoft Excel which involves you as the user being able to input some sort of formula and for it to apply to all selected cells. It works in many different ways. For example, it has the ability to auto fill so that it fills the cells with numbers from 1-100. Or days of the week, or months of the year. If you were creating a Gantt chart for project management, you would want to auto fill the consecutive days of which you want the project to run for.
