Explore the power of sealed classes in Java 17 through this GeeCON 2023 conference talk. Dive into the concept of "enums on steroids" as Marcin Chrost demonstrates how sealed classes can create innovative and facilitating mechanisms beyond strict control of class hierarchy. Learn about problem description, request-response patterns, evaluation techniques, response class hierarchy, immutable classes, and the evolution from ugly instance checks to elegant pattern matching. Gain insights into the compile-seal-compare process and engage with thought-provoking questions that challenge your understanding of this advanced Java feature.