It should be a DATE or DATETIME field type and the data should be saved in the format "YYYY-MM-DD" or "YYYY-MM-DD HH:MM:SS" you can then use MySQL's DATE_FORMAT() function to manipulate the output to any way you want, like
DATE_FORMAT('2006-02-26' '%m/%d/%y')
will out put
02/26/2006
, and also be able to do the comparisons you want.