These were made to help keep track of who's who on both sides of the family, but they have been used in many other ways, too. The letters are good for learning the alphabet, the family groupings allow games of Go Fish, and there are many different ways to rearrange by type (to see which side of the family has more members, to see if there are more boys than girls overall, to see how many people wear glasses, etc.).
Colors indicate relationships (all cousins have a blue background, for example), and the letters are placed to show maternal or paternal relationship (letters for people on the father's side are on the left, those for the mother's side on the right, as below).
