A great-grandparent is the parent of one of your grandparents. If you trace your family tree back three generations from yourself, you'll find your great-grandparents: your great-grandmother and great-grandfather on each side of your family.

Since most people have four grandparents (two on their mother's side, two on their father's side), most people have eight great-grandparents, though not everyone gets to meet them. Great-grandparents are often quite elderly, and many children know them only through stories and photographs.

When someone becomes a great-grandparent, it means they've lived long enough to see their own children have children, and then watch those children have children too. It's a special role that not everyone lives long enough to experience. Some lucky families have four or even five generations alive at the same time.

The pattern continues further back: a great-great-grandparent is your great-grandparent's parent, and you can keep adding “great” for each generation: great-great-great-grandparent, and so on. Each “great” represents another generation deeper into your family's past.