The United Kingdom is a constitutional monarchy. This means it has a Queen or a King. The Queen or King is decided by whether or not their parents, or other close relative, were King or Queen. Oldest brothers used to get to be King first, then the next brother, and so on, turning only to daughters when there were no sons. Queen Elizabeth II changed this, however, and rewrote the law so that the eldest child now becomes the next monarch no matter what that person’s gender is.