Security headers are HTTP response headers that help protect websites from various security threats. They instruct web browsers on how to handle content and can prevent attacks like cross-site scripting (XSS) and clickjacking. By implementing these headers, website owners can enhance their site's security posture. Common security headers include Content Security Policy (CSP), which controls which resources can be loaded, and X-Content-Type-Options, which prevents browsers from interpreting files as a different MIME type. Using these headers effectively helps safeguard user data and maintain the integrity of web applications.