This document discusses helping behavior and why people help others. It defines key concepts like altruism and prosocial behavior. Some reasons people help include social norms like reciprocity and social responsibility, sociobiology, social exchange to receive benefits, empathy and similarity to others. Social norms are social rules that people should help those who help them or depend on them. Social exchange theory suggests people help to maximize benefits and minimize costs. People are more likely to help those they feel empathy for or who are similar. Circumstances like mood, closeness to the person in need, and noticing the need also influence whether and how people provide help.