The word for a person who cares about what others think about him/her is "approval-seeking" or "validation-seeking." Such individuals often seek external validation and approval from others, and their self-esteem may be influenced by the opinions and perceptions of those around them. This behavior can stem from a variety of reasons, including a desire for social acceptance, fear of rejection, low self-confidence, or a need for reassurance. In some cases, seeking approval excessively can lead to compromising one's own values or needs to fit in or gain validation from others. It's essential for individuals who find themselves overly concerned about external validation to work on building self-confidence and self-acceptance to maintain a healthy sense of self-worth and independence from others' opinions.