Pride can be a good emotion and a positive personality trait, however it can also be negative, motivating a person to pursue selfish needs to satisfy their pride.
Pride can be useful when trying to maintain high standards. For example say someone is proud of an accomplishment, they will work hard to maintain that accomplishment and that pride. Pride can be personal pride, individual to a particular person. Pride can also apply to groups, small and large, it also applies to feeling pride for your country or nationality.
Pride is often the result of achieving something good after hard work and persistence. Someone who achieves wealth through hard work will feel a greater sense of pride for that achievement than say somebody who won or inherited their wealth.
Pride can also lead to feeling superior to others, looking down upon them, this is sometimes referred to as being prideful, similar to having a big ego or high self image.
The dark or shadow side of pride often shows itself when people start comparing their accomplishments to others. This comparing to others can either lead to feelings of superiority or inferiority. Feeling inferior can lead to vengeful and spiteful feelings which can become spiteful words or actions. These dark feelings will only hold us back and cause us problems.