Are we born with our fears or do we learn them? Why do our fears persist? What purpose does anxiety serve? How common are anxiety disorders, and which treatments are most effective? What's happening in our brain when we feel fear? This Very Short Introduction draws on the best scientific research to offer a highly accessible explanation of what anxiety is, why it is such a normal and vital part of our emotional life, and the key factors that cause it. Insights are drawn from psychology, neuroscience, genetics, epidemiology, and clinical trials.