A highly sensitive child is one of the fifteen to twenty percent of children born with a nervous system that is highly aware and quick to react to everything. This makes them quick to grasp subtle changes, prefer to reflect deeply before acting, and generally behave conscientiously. They are also easily overwhelmed by high levels of stimulation, sudden changes, and the emotional distress of others. Because children are a blend of a number of temperament traits, some HSCs are fairly difficult--active, emotionally intense, demanding, and persistent--while others are calm, turned inward, and almost too easy to raise except when they are expected to join a group of children they do not know. But outspoken and fussy or reserved and obedient, all HSCs are sensitive to their emotional and physical environment.