Everybody in the US knows that 21 is a big age. The first thing everyone immediately associates 21 with being able to drink, wild nights out, and general (legal) debauchery. You have finally crossed the last legal barrier into the adult world. Nobody can stop you now: you can buy cigarettes, alcohol, vote, drive, get a job, get a credit card, get a degree. In fact, many people will have a degree within a year or so of being 21.

However, 21 is not just a starting gate into the real world; it's also a finish line. 21 is the true end of childhood and adolescence. You are no longer a girl, but finally a women.

I'm going to speak for the girls on this one: from the age of about 13 or so, we are told that we have (or will become) women. There seemed to be many different checkpoints and starting gates for womanhood: the first period, the first pair of high heels, the first tube of lipstick, the first time.

I find these definitions of womanhood to superficial and stereotypical at best. At any of those points in time, I was not a woman; I was still a girl, ambling around in a body that could biologically function on the same level of that as an adult's.

Unfortunately, some associate the word "woman" with "old" as opposed to "girl," which denotes someone who is young and cute. So when do you start to feel like a "woman?"

Sometimes it's when you are called "ma'am" instead of "miss," and suddenly feel sad and self conscious that other people think you look old. You may google when is the right age to start using wrinkle cream.

Sometimes it's when you come across ridiculous articles titled something like "30 Things Women Over 30 Can't Wear Anymore." You click out of curiosity, because you realize you are over halfway there to age 30. You start to think about the things that you wear, the way you present yourself to the world, and realize that you may not always be able to shop in the juniors section of the department store. You peruse the women's section, and realize that it's a damn disaster: all of the clothes are boring and come in some hideous pattern with a weird accessory (like a belt or a pin) that you can't remove without destroying the entire garment. Seriously, what's up with that?

Again, these signals are superficial at best. I feel that 21 ushers you into true womanhood because of your experience and maturity.

Being a woman is when you realize that you can get in the car and go somewhere because you want to, even somewhere far.

It's when you work and have your own money, and start to think about how you want to spend it. You can spend it without answering to anyone. You start to spend extra on the things that you think are worth it, and also buy cheap stuff that's just as good as name brand. You know what's worth it to you.

It's when you stop worrying as much about what other people think about you or always trying to be the center of attention. You worry less about being the prettiest, most-liked girl in the room and you start to be yourself more. You have some confidence that you are a cool person, so why hide it? Plus, it matters less and less if guys (or girls) think you are the hottest girl in the room. Unlike in high school, it's just not important anymore.

It's when you can start to make more of your own decisions. Big decisions, like what to study, future careers, travel, relocation. People no longer look at you like a naive little girl who needs to be protected, but will start to respect that you are taking care of business for yourself.

It's when you can start to be a leader. As you get older, so does your family. And people may start to lean on you for comfort and direction, and you start to take on that larger role. Or perhaps at work, you've been around the block and have an idea of what needs to be done, and you start to offer guidance to the rookies.

It's when you stop idolizing ditzy but pretty movie/TV characters; Holly Golightly's helpless antics start to amuse you less, and you cringe a little watching your old favorite Disney princesses waiting for their princes come to rescue them. You kind of wish that they would make an executive decision for themselves ad move on.

It's when you start to look out for yourself, even in little ways. You always bring your wallet because you are not expecting people to pay for your meal or buy you things. You may have learned how to kill your own bugs, fix a couple of things, or set up electronics. You don't have to be Super Woman, but you are capable of handling your own small problems.

Most importantly, the separation between girls and women will be different for each person. All of the messages we are fed by the media and society are only illusions, because true women take their own power and create their own definitions and identities. What better time to start than 21?