This book serves as an introduction to the topic of gender. The term gender was first distinguished from sex in the 1950s, when psychologists began to discuss the idea of gender roles—behaviors and responsibilities given to people by a society rather than flowing from their biology. Over the last two decades, transgender people have expanded people’s understanding of gender even further, introducing to the mainstream the concept of gender identity, an individual’s understanding of their own gender. Along the way, there have been numerous debates and controversies: What is the influence of biology on gender? How does the media impact gender and gender roles? Do transgender people reinforce gender stereotypes or help to free us from them? The book explores these questions, providing basic definitions and tracing the history of gender as a concept; the role of biology, psychology, and culture on gender; and gender norms over time and across the globe.