The talk is about the tool Open Rewrite, which helps developers perform major migrations by automating the process from old technologies to the latest versions of Java and Spring. Open Rewrite allows migrations between versions of Java and Spring, as well as between frameworks, such as from JUnit to AssertJ and from Java.e to Spring. It uses a lossless semantic tree to minimize changes to the code and ensure safe code transformations. The talk explains how the tool works, its features, and what can be done with it, including migration, fixing static analysis findings, and enforcing code style. The company behind the tool, Moderna, is committed to making all recipes available on the Apache license for open source software.