A quick Google search of the word leadership gave me about 376 million results. And while it wouldn't give me the total for "leadership books" (if anyone knows, leave it in the comments), the same search on Amazon landed me with more than 100,000 possibilities.
With endless resources, the question of the day is "How do you define great leadership?" While I've read my fair share of books, I can confidently say that it boils down to this: Great leadership is about serving others.
More specifically, it's about serving your employees and putting them on equal par with customers (and sometimes even ahead of them). No, this doesn't imply giving the inmates the keys to the prison. It means empowering your knowledge workers and setting them up for success. It's what we're finding some of the best companies on the planet are doing. 
So what does that look like in practice, whether strategically through the eyes of the C-suite or at ground level if you're in a supervisory role? It means subscribing to the purest, yet most counterintuitive, form of leadership -- servant leadership.
But I'll be honest, what I'm suggesting here is what will ultimately appeal to human emotions and result in unprecedented business outcomes. More on that below.

The 5 Rare Signs of Great Leadership

If you've been told you're "leadership material," it may be due to these principles. If not, this is the standard to shoot for, whether you're looking to develop yourself as a leader or looking to hire people with the capacity to transform the workplace. Here's my question: Which of these have you heard others say make you a good leader? 

1. You connect exceptionally well with people.

Strong leaders connect with others with ease by showing their humanity. They accept that they're not perfect and that they make mistakes (and will admit to making them!). If the leader models authenticity, then, when employees make mistakes, it's safe for them to risk being open enough to say, "Hey, boss, I messed up." 

2. You involve all kinds of people and make them feel psychologically safe.

There are no lone rangers in leadership or a leadership culture of high performance. Good leaders aim to create a diverse environment of people with differing ways of doing things and viewing the world; they pump fear out of the room and allow for risks to be taken; and they let people feel safe to exercise their creativity, communicate their ideas openly, and provide input to major decisions. Because there's trust there, not fear. It communicates to employees a sense of "Hey, we're all in this together."

3. You show compassion.

Is it a natural tendency of yours to want to help others -- to alleviate people's suffering? While empathetic people have this ability to feel what others feel, compassion is a more objective form of empathy. It's feeling what others feel, but taking it to another level by doing everything in your power to remove the obstacles that stand in their way. The recently released Oxford Handbook of Compassion Science extensively documents and verifies that "compassionate management" leads to high organizational performance, innovation, customer retention, and profitability, and less employee turnover.

4. You are open and transparent.

People don't stress around you and teamwork isn't undermined because you share information and let everyone know what's going on at all times. In fact, studies prove that organizations that share privileged information with their employees -- typically reserved for the ivory tower in command-and-control power structures -- reduce uncertainty and alleviate stress about where they are headed and why. One example of openness, perhaps a bit extreme for most companies, is social media optimization company Buffer. It goes as far as posting its salary formula online for everyone to see, including what the CEO, Joel Gascoigne, makes. 

5. You understand human motivation and what makes people tick.

Perhaps someone has told you that you're really good at getting people to go above and beyond. Where does that come from? I venture to guess you're a student of positive psychology and understand what gets people from the neck up. Truth is, experiencing positive emotions is at the root of human motivation. Therefore, you'll find the best of leaders have a good understanding of human behavior, and what inspires people to perform their jobs at a high level. Companies should always hire or promote into leadership roles those who play to the strengths, gifts, and talents of employees. You'll find that they are the ones crafting and assigning work that is meaningful and has purpose (beyond a static job description) and brings out employees' passion and creativity.