The most common date format used by many are dd-mmm-yy or dd/mm/yy or mm/dd/yy. What has been neglected or remain unknown to most users is that Excel can return the day (e.g. Mon) of the date. When you entered “ddd” in custom format for a particular cell that contains a date value, the day is returned (see diagram). If you entered “dddd”, the full string (Monday) is returned. If you entered mmm, the 3 characters month name is return. By entering 4 “m”, the full month name (e.g. January) is returned.