Since it was first introduced decades ago, the concept of emotional intelligence has been heralded by many as the secret, intangible key to success. But as the idea has increased in popularity, it's also become widely misunderstood, and at times, criticized. Interestingly, even scientists, researchers, and others don't always agree on exactly what emotional intelligence is.

You may have read various, complex definitions for what makes up the concept of emotional intelligence. But we can actually sum up it up in a single, simple sentence:

Emotional intelligence is the ability to make emotions work for you, instead of against you.

You may be wary of trying to manage emotions--whether your own, or someone else's.

But before you dismiss the idea, consider just two examples of how this might look in real life:

Managing your emotions: Let's say you're involved in a conversation that suddenly turns from friendly disagreement to passionate argument. As you recognize the situation has become emotionally charged, you work hard to get your feelings "under control," even taking leave to prevent yourself from saying or doing something you'll later regret.

Managing others' emotions: On another occasion, you recognize that your conversation partner is speaking and acting irrationally, due to being in an emotional state, even as you remain calm. You then make efforts to defuse the situation...or gently change the subject. If it's necessary to continue the discussion, you decide to wait until the person is in a better frame of mind, and then give careful thought to how to broach the subject in the right way.

These are just two examples, and they're not one-size-fits-all. Certain issues require an immediate response. And in certain circumstances, it may be better for you to display your anger--as long as it's to the proper degree and you don't lose control of yourself.

But every day, we witness emotionally intelligent actions that make us and the people around us better. For example, consider the following:

One more thing: It's important to realize that emotional intelligence isn't inherently virtuous. Like any ability, it can be used both ethically and unethically; for example, psychologists have documented how narcissists and egomaniacs use such skills to bully or manipulate others.

But the best defense against being manipulated by those with high emotional intelligence...is to work to increase your own.

So whether you're trying to get the best out of yourself or your team, or looking to protect yourself from others who are trying to take advantage of your feelings, remember:

Work to increase your emotional intelligence.

And make emotions work for you, instead of against you.