Hacker101 is a free class for web security. Whether you're a programmer with an interest in bug bounties or a seasoned security professional, Hacker101 has something to teach you. Hacker101 is structured as a set of video lessons -- some covering multiple topics, some covering a single one -- and can be consumed in two different ways. You can either watch them in the order produced as in a normal class (§ Sessions), or you can watch individual videos (§ Vulnerabilities). If you're new to security, we recommend the former; this provides a guided path through the content and covers more than just individual bugs.