Companies often take a passive approach to culture. They figure it's not something they can control - or that they need to control. If they leave it alone, it'll all work itself out.

In her presentation, "The Best Things About Culture Are Free," at Culture Summit 2016, Katie Burke, chief people officer at Hubspot, says, "When it comes to culture, most companies have a can't-do attitude."

But leaving culture to chance does more harm than good for your organization.

Culture has always been important, but today, it's becoming more than just a buzzword. Culture is an important differentiator to set your company apart from the competition. It's also what attracts the right talent and brings in the right customers.

Plus, with more than 30% of the workforce now made up of Millennials, according to Pew Research Center, culture is more important than ever. Millennials want to work for companies that share their same values. They want to feel like their work has a purpose and makes a difference. In short, they want a good culture fit.

Still not convinced that you should put a bigger focus on culture? Here are four reasons why building culture is essential to the success of your organization.

1. Culture builds brand identity

Another way to characterize culture is to think of it as your brand's personality. Culture is what makes your brand unique and gives it that special edge. It puts your company's soul on display and tells the world who you are as a brand.

The more your audience understands and identifies with your brand, the more they'll want to buy from you. Your customers want to feel a connection with your brand, and it's your culture that will forge this bond.

When you define culture, you're also defining your company's values and goals. These will contribute to your company's mission and show your employees and the public what is most important to the brand.

In a blog post for Kissmetrics, Zach Bulygo, Kissmetrics' blog manager, writes, "When you put a focus on culture, you'll have guiding principles. People will know you for this. Employees will live by it. It'll help get you through difficult times. You'll base hiring and firing decisions on the principles. It'll help get all employees working on the same company mission. In some sense, it's the glue that keeps the company together."

2. Culture increases loyalty among employees

Your employees shouldn't dread coming to work. They should enjoy coming to the office and value the work that they do. Companies with a strong culture have employees who like the challenges of their job, get along well with their co-workers and enjoy the atmosphere of the workplace.

Culture gives employees a driving goal and purpose for what they do. It connects your leadership team with the rest of the employees and binds them with a set of shared beliefs. Your employees want to feel like they are contributing to something larger than themselves.

Jim Goodnight, CEO and co-founder of SAS, believes every company should set the bar high for culture. On the SAS website, he says, "Treat employees like they make a difference and they will."

Plus, employees who are more enthusiastic about the companies they work for tend to be more productive. That means more work and more business being done. Your employees' enthusiasm will also be apparent to your customers and be an attractive selling point for them.

As Simon Sinek, author of "Start With Why," writes on Twitter, "Customers will never love a company until the employees love it first."

3. Culture attracts and retains talent

While skillsets and experience are important when hiring new members for your organization, you also need to hire for culture fit. An employee's skills may get them in the door, but your culture is what will keep them there.

In his book, "The Advantage: Why Organizational Health Trumps Everything Else In Business," Patrick Lencioni, founder of The Table Group, writes, "Hiring without clear and strict criteria for culture fit greatly hampers the potential for success at any organization."

But why? Today, just 36.7% of employees are engaged at work, according to Gallup. Employees who are not engaged do not do their best work and are at risk of leaving your company. And with turnover costs estimated to range from tens of thousands to two times the candidate's annual salary, according to Josh Bersin of Deloitte, you can't afford to lose employees.

Hiring an employee is an investment, and you want to make sure you invest in the right people. By ensuring each individual you hire fits well with the company culture, you make it more likely they will stay with your company long term and contribute more to the success of the organization.

4. Culture makes advocates out of employees

So how do you find the right people to hire? Start by leveraging those engaged employees already working for you. LinkedIn finds companies can expand their talent pool by 10 times by recruiting through their employees' networks.

It's true that good talent knows other good talent. And when your employees are happy with their work, they are more likely to share with others. They'll spread the word about their positive experience with your company, and you'll soon gain a strong reputation.

Encourage and motivate your employees to speak positively on your brand's behalf. Not only will they help you find the right people to hire, but they can also help you bring in more customers.

No matter which way you slice it, employees want to feel that they belong. You need to build a community within your organization that people want to be a part of. Make your culture the foundation of that community.

How have you fostered a strong culture within your organization? What initiatives have you launched? Share your strategies in the comments below: