Recommend a free photo album with tags

My dad is now really into shooting digital pictures and movies, because of the grandkids, and he’s getting bogged down in the organization, because if you just use Windows, you have to manually retitle each picture by hand.

I’m wondering if there’s a program that lets you tag pictures with multiple attributes, so that you can have the same picture in multiple groups, kind of like Flickr does. And it would be nice if you could just drag the pictures into the tagged group to create the tag. Am I just dreaming here?