3 Unwritten Rules of the Corporate World That Women Need to Know These are the things companies don't cover during orientation or in the employee handbook.

Do you know what you need to do to succeed at your company? One major challenge is that beyond your defined job responsibilities there are unwritten rules of U.S. corporate culture that aren't covered in any orientation or employee handbook. These unwritten rules were formed decades ago when the workplace was predominantly male.

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Unwritten behavioral norms that arose in workplace cultures dominated by men may seem foreign to women due to differences in upbringing. Many women are raised not to call attention to their own accomplishments or intelligence. Furthermore, many women, especially women of color, are socialized to believe that taking center stage is unladylike and improper. Many men do not receive the same messaging. This difference in messaging ends up putting women at a disadvantage as they navigate their careers.

Far too often, hardworking, intelligent women get passed over for promotions and overlooked for high-profile work assignments and just don't know why. One reason this happens is because women often don't know about the unwritten rules of corporate culture or how to effectively act in accordance with them.

To help level the playing field for women, here are three foundational, unwritten rules of the U.S. corporate world. If you want to advance into leadership at your company, ask yourself if you have been investing time and resources into each of these areas.

1. Recruit a sponsor.

Both mentors and sponsors give advice, provide feedback and make introductions to people in their networks. The key difference is that sponsors are people who are in "the room where it happens," to reference the Hamilton song. Sponsors are people who have power and influence and are willing to use their position to advocate on your behalf.

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When the Center for Talent Innovation (CTI) asked professionals if they had a sponsor, only 13 percent of female professionals and just 8 percent of professionals of color reported having a sponsor, compared to 40 percent of their non-diverse peers. Lack of sponsorship is likely one of the reasons why there are so few diverse leaders in the corporate world. Read Sylvia Ann Hewlett's book Forget a Mentor, Find a Sponsor to get a clearer sense of what good sponsors do. Remember that if an individual either a) lacks the necessary power and influence or b) is not willing to advocate on your behalf, then he or she is not your sponsor.

Relationships with sponsors do not just go one way -- ensure you are an excellent protegé and give back to your sponsors when the opportunities arise. Also, don't conflate sponsors and mentors. They are each important to career success but different in role and function. Mentors can be at your level or higher than you. Sponsors by definition are higher because they are in a position of power and influence. Mentors can help guide you and provide informal feedback and information. Sponsors need to be willing to put their "chips" on you, but they don't have time for every question you may have. That is what your mentor is for.

2. Strategically self-promote.

In the U.S. corporate world, it is expected that you will highlight your accomplishments. If you don't, your unspoken accomplishments will be overshadowed by the accomplishments of your office mates who ensure their good news is circulated through the office chatter.

The default perception is that a worker is average or below average, unless demonstrated otherwise. If people start off with a neutral or negative perception of your ability, it is your responsibility to present them with positive facts about yourself, so they can form a more accurate, positive perception of you. This is particularly important if you are a diverse professional, because you will likely have to push back against negative stereotypes often associated with your identity.

Effective self-promotion is about being proud of what you worked hard to accomplish and willingly sharing those stories with others. For self-promotion strategies on how to develop your story and deliver it with conviction, read BRAG! The Art of Tooting Your Own Horn without Blowing It by Peggy Klaus.

Related: Why Working Women Need to Mentor Other Women

3. Invest in your professional appearance.

Before we even open our mouths, we make an impression just by how we present ourselves. Your colleagues may judge your level of professionalism and bucket you into a particular social class by the way you dress. If you are a diverse professional, the way you dress may support or contradict the unconscious stereotypes that people may carry in their heads. Therefore, be mindful about managing your image and consider how it will be viewed by others.

One of the best examples of image management is Beyonce. You rarely find an ugly image of Beyonce on social media or even in print. Reportedly, Beyonce spends $1 million per year on hair, makeup and other self-care. You don't need to spend $1 million, but when presenting yourself, make sure others see you the way you want to be seen.

As a guide on how to dress, look to the people in leadership positions at your organization. There may be some quirky leaders at your office with a unique sense of style but defer to the majority of your senior colleagues. For example, Mark Zuckerberg, CEO of Facebook, may wear jeans and a T-shirt to work, but you don't see Sheryl Sandberg, COO of Facebook, dressing that way. Emulate the level of professional appearance of your organization's leaders to the extent that your budget will allow. Looking the part is an important component of rising through the ranks.

Pay attention to what matters.

Continue to work hard each and every day, but also focus on some of the other areas that matter: recruiting sponsors, strategically self-promoting and investing in your professional appearance. With insider knowledge of some areas that often get overlooked, you can be more strategic and less reactive in your career.