This document provides an introduction to key gender concepts. It defines gender and differentiates it from sex. Gender refers to socially constructed characteristics and roles of women and men, while sex refers to biological differences. The document outlines differences between gender and sex roles. It explores the relationship between gender and power. It also defines related terms like gender equality, equity, mainstreaming, empowerment, and analyzes approaches like gender-neutral, aware and transformative. The document discusses realities of gender disparities and potential gains from reducing them, such as increased agricultural outputs and reduced hunger. It compares Women in Development and Gender and Development approaches. Finally, it defines practical and strategic gender needs.