Leadership theories have evolved over time from trait theories that focused on innate qualities, to behavioral theories examining leader actions, to contingency and situational theories incorporating contextual factors. Modern approaches include charismatic leadership theory emphasizing vision, values and emotional commitment. The document discusses various leadership definitions, styles, and influential models such as Fiedler's contingency model, Hersey-Blanchard situational theory, and path-goal theory. It analyzes different bases of power and influence tactics available to leaders.