In many cases, knowing when something happened is just as important as knowing what happened. If you ran a garden supply store or nursery, for example, it would be useful to know that you get most of your customers on the weekends but that you make most of your large sales (most likely to landscape architects and other stores) during the week. Excel recognizes when you enter a date into a cell and applies the program’s default format to the date. There are many date formats to choose from, though—pick the one you like the best!