To a lot of us, the idea that gender extends beyond simply male and female can be confusing.
"It's a boy!" "It's a girl!" We're labeled with a gender as far back as the moment we were born.
But somewhere along the way, some people realize that terms like "male," "female," "man," "woman," "boy," and "girl" don't properly describe their own sense of self.
Some people simply don't fit neatly into those boxes — demonstrated here by YouTube jack-of-all-trades Lindsay Penn — and so many of them have sought out terms that more accurately describe who they are.
In May 2015, Dictionary.com added three new words to its database to help describe some of these nonbinary (not simply male or female) genders.
First, there's the word "agender," which is essentially someone without a gender at all.
Then there's "bigender," a term used to describe someone who may most closely identify with both male and female genders.
And then finally, there's "gender-fluid," used to describe someone whose gender shifts between male, female, and everything in between.
If it sounds like these three terms are describing the same thing (at first glance, they certainly might), try thinking about it as though you're dividing blocks into groups.
If you look at this image, it's pretty easy to divide these blocks into groups according to color, right?
You've got two yellow, two red, and one orange. Right? It's simple.
But what if it's not always so clear cut? And what if instead of there being three colors to choose from, you had the option to select from hundreds?
You could still make the case that there are two yellow, two red, and one orange, but it's not quite accurate.
Because some colors (like #2 and #4) don't quite neatly fit into the previously arranged groups. # 2 is kind of a yellow-orange; #4 is kind of an orange-red.
Gender is a lot like that. Often, we simplify it into these clear-cut boxes: male and female. The issue is that not everyone fits those boxes, and that is OK.
Just as boxes #2 and #4 are no less real colors than #1 and #5, people whose genders don't fit neatly into the categories of male or female are no less valid than those who do.
Gender can be confusing. Just like the Doctor here explains time travel, gender is like that — just more ... gender-y.
And just as boxes #2 and #4 are outside the main groups, they're still very different colors.
Agender, bigender, and gender-fluid identities are outside of the male-female binary, but are still distinct and different from one another.
Last year, Australian model and actress Ruby Rose came out as gender-fluid.
Rose did so after releasing a video called "Break Free" (seriously, watch it). In an interview with News.com.au, Rose said, “I am very gender fluid and feel more like I wake up every day sort of gender neutral."
But what if you're not sure what gender someone is? Don't worry about it.
You can't tell someone's gender just by looking at them. Gender isn't what kind of genitals you have. Gender isn't whether you act a certain way or dress a certain way. Gender is a core sense of self that someone has, and it might not line up with what you picture visually.
If someone tells you what gender they are? Great! Please take them at their word.
If they don't, and you're not sure? Don't worry about it.