It is the ability to identify with the feelings and experiences of another. This goes beyond telling a friend you know how he or she feels. When you possess true empathy, you actually experience the emotion on the same level of the other person. At a very mild level, empathy is what causes you to cry during those Hallmark commercials. The imagery and story touches your own experiences and triggers your emotional recall of the accompanying feelings.
Children are often very high-level empaths.
I felt the fear and wanted to be able to do something about it.