You know that little bump that's on your tummy, right where your belly button is? Well, in movies, TV shows, and other things people see for fun, sometimes that bump is shown off in a special way.
Back in the old days, people in movies and on TV never showed their bellies or belly buttons, because it wasn't considered proper. But then, in the 1960s and 70s, people started to loosen up a bit and it became more common to see women wearing clothes that showed off their tummies.
As time went on, the belly button took on a special meaning. It became sort of a symbol of sexiness, and people started to focus on it a lot more. Sometimes you'll see pictures of models or movie stars showing off their belly buttons in magazines or online.
So, the navel (which is just another fancy name for belly button) has become pretty popular in our culture, especially when it comes to fashion and looking good. But don't worry if you don't have an "outie" belly button like some people - all belly buttons are neat and important!