It's called empathy - the capacity to recognize and share feelings that are being experienced by another sentient or semi-sentient being. Someone may need to have a certain amount of empathy before they are able to feel compassion. (Wikipedia)
That was a textbook definition but having lived with it I can say a lot more about it. Empathy is the capacity that turns a human being (and I hope you're good with metaphors) into an emotional sponge. We often say to other people that they have no idea of what is like experiencing certain feeling, happiness or pain, being empathetic gives you this unique chance to match your emotions to another person's emotions.
Empathy is a word of many definitions, it means carrying for other people and having the desire to help them, you sense their need for help, they often don't ask for it but you know anyway. You know what other people think or feel, they are like an open book to you, you "read" them without any difficulties, it's not just some theories because from my own experience I can tell it's true.
People can often try to hide their feelings, crawl into their own little world far from others, but they won't hide from empathetic people because they can see through. They can see behind the masks.
Empathy it's not just a language I can read, it's a language I can speak too.
We should not confuse empathy with sympathy, later one being a derivative from empathy, you can show sympathy being a little empathetic first and not the other way around.
How to recognize an empathetic person ?
Empathetic people are usually warm, affectionate, tender, endearing, those exact words, no exaggerating. They won't feel awkward or embarrassed in case they see you cry, and perhaps they will cry too just you won't feel alone. They are not afraid of shedding some tears, crying for them it's not something to be embarrassed about. Soon they come to realize that the emotions they've been experiencing during those moments are inhumanly strong and difficult to control and they share them back, they keep it mutual, sharing it's one of their things. They trust you, by default, that you can overcome different difficult situations, they inspire you with enough self-confidence to do that. They point out your strengths, they remind you what are you made of, remind you of you can do and can achieve. They simply know you, empathetic people are the most trustworthy people. Before advising you, giving you directions they put themselves in your situation, they feel what you feel even if sometimes it might be something that is too much for them, even if it might hurt them.
The bad part of being empathetic.
As I said earlier they can't control what to feel and what not to feel, it's simply uncontrollable, they may have superpowers but same empathy may signify their fatal kryptonite. Some people may think that empathetic people are blessed and see only the positive in the world, that they get the perks of life, well, they're mistaken.
As a blogger (Andrei Roșca) said in his article about empathy that the good side comes with the bad side, it's a package deal, you either have them both, or you don't have them at all.
Empathetic people tend to over-think everything, who (masochistically) like to solve puzzles, problems that are not even theirs to solve, they tend to think that the solution lies within the problem, at the origins of the problem. These people are the ones who don't sleep at night, they would rather solve problems in their heads than sleep.
These people tend to live faster, with an astonishing intensity, they consume themselves emotionally, as I mentioned before, they are human sponges absorbing emotions and rather than letting go of what once used to be problems they keep it inside them, for them experience it's meaningful and useful at all times.
To end on a positive note I would say being empathetic is good, it's comforting most of the time, it's what makes your relationships run smoothly, help you bond with others on deeper levels, it helps you understand why people react or even lack reaction to certain situations, it bring you one step ahead of everyone when it comes to knowing what people need, want, desire, feel and so on.
I stumbled upon an interesting article at which I just took a peek at, have yet to read it but I can totally recommend it to you "What's Empathy Got to Do With It?.
I like a quote from it "I am not good at empathy. Will you settle for sarcasm?", well I'm both, empathetic and sarcastic because unfortunately in some societies empathy it's not fully understood and accepted and sarcasm is a nice tool to make fun of idiots without letting them actually know about it.
Glad I had you as a reader. Hope to see you soon.